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 A358880 #14 Dec 25 2022 14:02:52 %S A358880 4,16,121,484,625,1089,10201,14641,19881,40804,49284,69696,91809, %T A358880 94249,203401,698896,1002001,1234321,1490841,1517824,4008004,4276624, %U A358880 4460544,4937284,5313025,6325225,6895876,6948496,7706176,9018009,15665764,15776784,16120225 %N A358880 Squares of the form k + reverse(k) for at least one k. %F A358880 a(n) = A356648(n)^2. - _Michel Marcus_, Dec 25 2022 %e A358880 56 + reverse(56) = 56 + 65 = 121 = 11^2, so 121 is a term. %o A358880 (Python) %o A358880 from math import isqrt %o A358880 def aupto(lim): return sorted(set(t for t in (k + int(str(k)[::-1]) for k in range(1, lim+1)) if t <= lim and isqrt(t)**2 == t)) %o A358880 print(aupto(10**7)) # _Michael S. Branicky_, Dec 25 2022 %Y A358880 Cf. A000290, A067030, A356648. %K A358880 nonn,base %O A358880 1,1 %A A358880 _Jon E. Schoenfield_, Dec 04 2022