A181895 Difference between maximum and minimum positive value y in solutions to x^2 - y^2 = n!.

4, 28, 176, 1258, 10070, 90692, 907184, 9979181, 119750111, 1556754911, 21794572379, 326918591535, 5230697470143, 88921857013919, 1600593426385151, 30411275101997759, 608225502043759679

Offset: 4

Author

Artur Jasinski, Mar 31 2012

Keywords

• nonn
• easy

Programs

Mathematica

cc = {}; Do[f = n!/4; x = Max[Select[Divisors[f], # <= Sqrt[f] &]]; kk = f/x - x; kkk = ((n! - 4)/4); AppendTo[cc, kkk - kk], {n, 4, 20}]; cc

Formula

a(n) = A139174(n) - A038202(n).