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 A069085 #13 Jun 06 2016 07:28:48 %S A069085 120,672,45840,51168,523776,459818240,1476304896,51001180160 %N A069085 Abundant numbers n such that n = sigma(k) - 2k, where k = sigma(n) - 2n. %C A069085 All triply perfect numbers (A005820) are in the sequence, as are 45840 and 51168. Are there any other terms? %C A069085 a(8) > 10^10. - _Donovan Johnson_, Apr 22 2012 %C A069085 a(9) > 1.3*10^11. - _Giovanni Resta_, Jun 06 2016 %e A069085 sigma(45840) - 2*45840 = 51168 and sigma(51168) - 2*51168 = 45840, so 45840 and 51168 are in the sequence. %t A069085 For[n=1, True, n++, k=DivisorSigma[1, n]-2n; If[k>0&&DivisorSigma[1, k]-2k==n, Print[n]]] %Y A069085 Cf. A005820. %K A069085 more,nonn %O A069085 1,1 %A A069085 _Naohiro Nomoto_, Apr 05 2002 %E A069085 Edited by _Dean Hickerson_, Apr 11 2002 %E A069085 a(7) from _Donovan Johnson_, Apr 22 2012 %E A069085 a(8) from _Giovanni Resta_, Jun 06 2016