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 A102359 #10 Feb 22 2020 02:30:07 %S A102359 1,6,32,108,384,2688,5632,27864,153920,499968,1477440,11708928, %T A102359 22380544,115568640,620101632,1826150832,5726797824,54044390400, %U A102359 91626668032,555102471168,2352412508160,7458459886080,23955459951744,199536712962048,425355918188544,1849167560835072 %N A102359 a(n) = sigma((4^n - 1)/3), where sigma(n) is the sum of positive divisors of n. %H A102359 Amiram Eldar, <a href="/A102359/b102359.txt">Table of n, a(n) for n = 1..603</a> %F A102359 a(n) = A000203(A002450(n)). - _Amiram Eldar_, Feb 21 2020 %o A102359 (PARI) a(n) = sigma((4^n - 1)/3); \\ _Michel Marcus_, Feb 21 2020 %Y A102359 Cf. A000203, A002450. %K A102359 nonn %O A102359 1,2 %A A102359 Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 22 2005 %E A102359 More terms from _Amiram Eldar_, Feb 21 2020