A139151 a(n) = (n!+4)/4.

7, 31, 181, 1261, 10081, 90721, 907201, 9979201, 119750401, 1556755201, 21794572801, 326918592001, 5230697472001, 88921857024001, 1600593426432001, 30411275102208001, 608225502044160001, 12772735542927360001

Offset: 4

Author

Artur Jasinski, Apr 11 2008

Keywords

• nonn
• easy

Comments

Maximal solution for x such that x^2-y^2 = n! (because ((n! + 4)/4)^2 - ((n! - 4)/4)^2 = n! ). - Artur Jasinski, Mar 31 2012

Links

• Amiram Eldar, Table of n, a(n) for n = 4..450

Crossrefs

Cf. A139149, A139150, A139152, A139153, A139154, A139155, A139156, A139157.

Programs

Mathematica

Table[(n! + 4)/4, {n, 4, 30}]

PARI

a(n)=n!/4+1 \\ Charles R Greathouse IV, Jun 20 2012