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 A305718 #9 Jun 10 2018 12:00:01 %S A305718 1,6976,15,35,39,51,95,831,45,88,63,222,135,37888,96,284,117,354,175, %T A305718 84,153,176,3893,267,210 %N A305718 a(n) is the smallest number k such that sigma(k + 2n) = sigma(k) - 2n, or -1 if no such number exists. %C A305718 Even-indexed terms of A304994. %C A305718 If it exists, a(25) > 10^9. Other large (if existent) terms include a(55), a(73), and a(97). %C A305718 Terms a(26)..a(54) are 120, 160, 228, 339, 602, 156, 1393, 425, 279, 1204, 462, 70912, 231, 488, 633, 1099, 575, 228, 369, 1211, 387, 364, 605, 579, 396, 725, 1731, 1146, 455. %C A305718 a(25) > 10^12, if it exists. - _Giovanni Resta_, Jun 10 2018 %F A305718 a(n) = A304994(2n). %Y A305718 Cf. A304994. %K A305718 nonn,more %O A305718 0,2 %A A305718 _Jon E. Schoenfield_, Jun 08 2018