This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A117756 #16 Sep 13 2024 00:39:22 %S A117756 0,1,4,9,36,64,81,100,121,144,225,324,361,400,441,576,729,900,1089, %T A117756 1225,1296,1521,1764,2025,2116,2304,2601,2916,3025,3249,3600,4356, %U A117756 4761,5041,5184,5625,6084,6400,6561,7056,8100,9216,9801,10000,10201,10404,11025 %N A117756 Squares for which the reversed sum of the digits is also a square. %e A117756 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. %t A117756 Select[Range[105]^2, IntegerQ@ Sqrt@ FromDigits@ Reverse@ IntegerDigits@ # &[Total@ IntegerDigits@ #] &] (* _Michael De Vlieger_, Jan 15 2016 *) %o A117756 (PARI) isok(n) = issquare(n) && issquare(eval(concat( Vecrev(Str(sumdigits(n)))))); \\ _Michel Marcus_, Jan 15 2016 %Y A117756 Cf. A053057 (squares whose digit sum is also a square). %K A117756 base,nonn %O A117756 0,3 %A A117756 Luc Stevens (lms022(AT)yahoo.com), Apr 14 2006 %E A117756 a(34) corrected by _Vincenzo Librandi_, Jan 15 2016