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A242538
Squares that are sum of digits of factorials.
0
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
1,2
COMMENTS
Intersection of A000290 and A004152.
EXAMPLE
a(5)=144 for 33!=8683317618811886495518194401280000000 whose sum of digits is 144=12^2. a(5) is also originated from 34! and 35!.
MATHEMATICA
Union[Select[Total[IntegerDigits[#]]&/@(Range[2500]!), IntegerQ[Sqrt[#]]&]] (* Harvey P. Dale, Feb 20 2015 *)
PROG
(PARI) lista(nn) = {v = vector(nn, n, sumdigits(n!)); Set(select(x->issquare(x), v)); } \\ Michel Marcus, May 18 2014
CROSSREFS
Cf. A066235.
Sequence in context: A297584 A073946 A016766 * A083353 A083014 A202287
KEYWORD
nonn,base
AUTHOR
Carmine Suriano, May 17 2014
STATUS
approved