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 A113286 #32 Feb 16 2025 08:32:59 %S A113286 30240,32760,859320,898560,2096640,2178540,2234232,23569920,45532800, %T A113286 54996480,61281792,142990848,422688000,436205952,1379454720 %N A113286 Numbers k such that S(S(k))=k, with S(n)=sigma(n)/4: 1/4-sociable numbers of order 1 or 2. %C A113286 a(1) and a(2) are 4-perfect numbers (A027687). a(4) = S(a(3)). %C A113286 a(6), a(8), a(9), a(12), and a(15) are also 4-perfect numbers (A027687). - _Michel Marcus_, Feb 23 2014 %H A113286 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SociableNumbers.html">Sociable Numbers</a> %o A113286 (PARI) isok(n) = (type(s= sigma(n)/4) == "t_INT") && (sigma(s)/4 == n); \\ _Michel Marcus_, Feb 20 2014 %Y A113286 A027687 is a subsequence. %Y A113286 Cf. A113546 (1/3-sociable numbers). %Y A113286 Cf. A355279 (1/4-sociable numbers of order 1 or 3). %K A113286 nonn,more %O A113286 1,1 %A A113286 _Yasutoshi Kohmoto_, Jan 27 2006 %E A113286 a(5)-a(15) added by _Michel Marcus_, Feb 24 2014