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 A125303 #13 Apr 03 2022 01:29:28 %S A125303 891,941,2931,5401,78281,861761,67304951,77171861,757603751, %T A125303 6346449411,6517798231 %N A125303 Each number in this sequence is the reversal of the sum of its proper substrings. %e A125303 For example, the sum of the proper substrings of 891 is 8 + 9 + 1 + 89 + 91 = 198 and 198 reversed is the number itself. %e A125303 5401 is included because 540 + 401 + 54 + 40 + 5 + 4 + 0 + 1 = 1045, which is 5401 backwards. %o A125303 (Python) %o A125303 def ok(n): %o A125303 w = str(n) %o A125303 ss = set(int(w[i:j+1]) for i in range(len(w)) for j in range(i, len(w))) %o A125303 return n > 9 and n == int(str(sum(s for s in ss if s != n))[::-1]) %o A125303 print([k for k in range(80000) if ok(k)]) # _Michael S. Branicky_, Apr 02 2022 %K A125303 base,more,nonn %O A125303 1,1 %A A125303 _Tanya Khovanova_, Dec 09 2006 %E A125303 More terms from _Paul Richards_, Sep 25 2007 %E A125303 a(7)-a(11) from _Donovan Johnson_, Nov 30 2008