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 A240754 #7 Aug 26 2021 07:03:57 %S A240754 8,26,53,98,107,143,161,170,179,188,224,233,242,260,269,278,287,296, %T A240754 350,368,386,404,413,431,449,476,494,503,539,548,557,584,593,629,638, %U A240754 647,674,683,737,746,773,791,818,827,863,872,908,926,944,998,1007,1043 %N A240754 Numbers k with digit_sum(k*k) - 1 = digit_sum((k+1)*(k+1)). %C A240754 A240752(a(n)) = 0. %H A240754 Reinhard Zumkeller, <a href="/A240754/b240754.txt">Table of n, a(n) for n = 1..10000</a> %o A240754 (Haskell) %o A240754 import Data.List (elemIndices) %o A240754 a240754 n = a240754_list !! (n-1) %o A240754 a240754_list = elemIndices (-1) a240752_list %o A240754 (Python) %o A240754 def ds(n): return sum(map(int, str(n))) %o A240754 def ok(n): return ds(n*n) - 1 == ds((n+1)*(n+1)) %o A240754 print(list(filter(ok, range(1044)))) # _Michael S. Branicky_, Aug 26 2021 %Y A240754 Cf. A202089, A239878, A004159, A007953, A000290. %K A240754 nonn,base %O A240754 1,1 %A A240754 _Reinhard Zumkeller_, Apr 12 2014