![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F9b553add-f9f4-4eee-bfcd-f9437058619b%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3D299afe91aeefd743fb8f370d5238cf9c07c2307a5ab0937a75dee0a52d999ed4%26X-Amz-SignedHeaders%3Dhost?table=block&id=53a408b9-87e3-4616-91ff-33b0b69d1370&cache=v2)
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F0716275e-203d-4557-bfc7-9931d933ed05%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3D5b75cf0aaa88bdf54b9acf5e4c01f242583f628474e36bcaf7e81fd6980bb79d%26X-Amz-SignedHeaders%3Dhost?table=block&id=1836df1e-3d9a-49df-bcaa-5bf086737da9&cache=v2)
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fb797d36d-7b49-4b64-83c2-41957d7b4d15%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3De378cd01099fa6f4b09e09785eb948f911147281af2e820778f4cf7418a8528b%26X-Amz-SignedHeaders%3Dhost?table=block&id=aa806492-59f8-4494-8d8b-e61d1b16e993&cache=v2)
s : 3 시작, t : 2씩 곱, number : 5번째 항까지
결과적으로 5번째 항인 48이 구해진다.
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F9eda85c9-64f9-4208-a4d6-fa54026b3631%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3Dbb4f05335685f9a9a8907625469f1916d8b0673f16534562994a2b4473345d40%26X-Amz-SignedHeaders%3Dhost?table=block&id=e8373f69-8038-4e3d-aa87-f1840e8d1d74&cache=v2)
팩토리얼과 피보나치는 아주 익숙하다.
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Faf40f2e0-a545-466f-8c2f-02f633477c6e%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3D3e51d1f41e4e204b1c413047c92e4ea5ab7f6f28835a0ebc1485a285206996e2%26X-Amz-SignedHeaders%3Dhost?table=block&id=a04f4379-ebbc-439f-afa9-f51d4ec2bd20&cache=v2)
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fb76cf1a8-6256-4763-99a9-9dd3ca9d5d07%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3D282a470f4980e40f1f5c6b8eb5c41dd18ff6741f7eb13d6afa36d367687b6836%26X-Amz-SignedHeaders%3Dhost?table=block&id=0b52b1bd-066d-43ce-93d6-b9261e1a1610&cache=v2)
![notion image](https://www.notion.so/image/https%3A%2F%2Fs3.us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Feb744d98-8253-446a-80fc-04dfba340e18%2FUntitled.png%3FX-Amz-Algorithm%3DAWS4-HMAC-SHA256%26X-Amz-Credential%3DAKIAT73L2G45O3KS52Y5%252F20211025%252Fus-west-2%252Fs3%252Faws4_request%26X-Amz-Date%3D20211025T151956Z%26X-Amz-Expires%3D86400%26X-Amz-Signature%3Dbed58033d352d8998a23e037265c294737417e8b635ea6a9d14308fc27921e99%26X-Amz-SignedHeaders%3Dhost?table=block&id=c0be3d02-6e83-42d3-b5f2-bb7bdd2e2b02&cache=v2)
가장 큰 항을 주면 필요한 항의 값을 찾아들어간다. 0과 1번째 항은 값을 알기 때문에 이 값을 만나고 나면 역으로 계산되어 f(4)와 f(3)의 값이 완성된다.
참고로 여기서 f(3)이나 f(2) 등의 한번 구한 값은 메모이제이션을 해서 다시 연산하지 않고 갖다 쓸 수 있게 하면 동적계획법(Dynamic Programming)이라고 한다.