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 A074238 #10 Aug 10 2025 20:48:42
%S A074238 1,8,26,53,3087,6173,8091,12330,18358,42898,294847,27382381,49290155,
%T A074238 426131190,1350661780,3161620702,4461944219,17625479383,40766706170,
%U A074238 61554358125,270930998357
%N A074238 Numbers k such that the sum of the reverses of 1,2,...,k is a perfect square.
%C A074238 a(22) > 5*10^11. - _Giovanni Resta_, Apr 16 2017
%e A074238 reverse(1) + reverse(2) + ... + reverse(25) + reverse(26) = 1 + 2 + ...+ 52 + 62 = 729 = 27^2, so 26 is a term of the sequence.
%t A074238 s = 0; r = {}; For[i = 1, i <= 10^5, i++, s = s + FromDigits[Reverse[IntegerDigits[i]]]; If[IntegerQ[s^(1/2)], r = Append[r, i]]]; r
%Y A074238 Cf. A062918.
%K A074238 base,nonn
%O A074238 1,2
%A A074238 _Joseph L. Pe_, Sep 19 2002
%E A074238 a(11)-a(21) from _Giovanni Resta_, Apr 16 2017