A117756 Squares for which the reversed sum of the digits is also a square.
0, 1, 4, 9, 36, 64, 81, 100, 121, 144, 225, 324, 361, 400, 441, 576, 729, 900, 1089, 1225, 1296, 1521, 1764, 2025, 2116, 2304, 2601, 2916, 3025, 3249, 3600, 4356, 4761, 5041, 5184, 5625, 6084, 6400, 6561, 7056, 8100, 9216, 9801, 10000, 10201, 10404, 11025
Offset: 0
Examples
729 is in the sequence because (1)it is a square, (2)the sum of its digits is 7+2+9=18 and (3)18 reversed is 81, which is a square.
Crossrefs
Cf. A053057 (squares whose digit sum is also a square).
Programs
-
Mathematica
Select[Range[105]^2, IntegerQ@ Sqrt@ FromDigits@ Reverse@ IntegerDigits@ # &[Total@ IntegerDigits@ #] &] (* Michael De Vlieger, Jan 15 2016 *)
-
PARI
isok(n) = issquare(n) && issquare(eval(concat( Vecrev(Str(sumdigits(n)))))); \\ Michel Marcus, Jan 15 2016
Extensions
a(34) corrected by Vincenzo Librandi, Jan 15 2016