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

4,1

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

Table of n, a(n) for n=4..21.

Mathematica

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

Prog

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

Crossrefs

Sequence in context: A208446 A172634 A322205 * A139060 A324621 A223144

Adjacent sequences: A139148 A139149 A139150 * A139152 A139153 A139154

Keyword

nonn,easy

Author

Artur Jasinski, Apr 11 2008

Status

approved