A242538 Squares that are sum of digits of factorials.

1, 9, 36, 81, 144, 225, 324, 441, 729, 1089, 1296, 2025, 2304, 2601, 2916, 3249, 3600, 3969, 4356, 4761, 6561, 7056, 7569, 8100, 8649, 9216, 9801, 10404, 11025, 11664, 12996, 13689, 15129, 16641, 17424, 20736, 22500, 23409, 26244, 29241

Offset: 1

Author

Carmine Suriano, May 17 2014

Keywords

• nonn
• base

Comments

Intersection of A000290 and A004152.

Examples

			a(5)=144 for 33!=8683317618811886495518194401280000000 whose sum of digits is 144=12^2. a(5) is also originated from 34! and 35!.
		

Crossrefs

Cf. A066235.

Programs

Mathematica

Union[Select[Total[IntegerDigits[#]]&/@(Range[2500]!),IntegerQ[Sqrt[#]]&]] (* Harvey P. Dale, Feb 20 2015 *)

PARI

lista(nn) = {v = vector(nn, n, sumdigits(n!)); Set(select(x->issquare(x), v));} \\ Michel Marcus, May 18 2014