A328955 a(n) = smallest integer k such that the decimal expansion of k! starts with the first n digits of Pi.

9, 62, 62, 10044, 50583, 1490717, 5573998, 65630447, 688395641, 5777940569, 77773146302, 1154318938997, 1544607046599, 119027672349942

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Chinese BBS, Factorial and Pi

Ickiverar, C Code for the result

Example

9! = 362880 is the smallest factorial that begins with 3, so a(1) = 9.
62! = 314699..., whose first 3 digits are 314; no integer less than 62 has 314 as the first 3 digits of its factorial, no does any integer less than 62 have 31 as the first 2 digits of its factorial, so a(2) = a(3) = 62.

Crossrefs

Cf. A000142 (factorial), A000796 (Pi).

Sequence in context: A322086 A075139 A264376 * A098921 A027234 A081574

Adjacent sequences: A328952 A328953 A328954 * A328956 A328957 A328958

Keyword

nonn,hard,more,base

Author

Zhao Hui Du, Nov 01 2019

Extensions

a(14) from Ickiverar added by Zhao Hui Du, Jan 10 2020

Status

approved