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 A352690 #20 Jan 31 2025 17:42:17 %S A352690 0,1,5,53,76,245,1647,5257,20336,30940,124837,374756,1205149,2643792, %T A352690 7516934,29855796,102243621 %N A352690 Index of 2^n-1 in A353709. %C A352690 This sequence is strictly increasing. %H A352690 Rémy Sigrist, <a href="/A352690/a352690.txt">C++ program</a> %e A352690 A353709(1647) = 63 = 2^6 - 1, so a(6) = 1647. %o A352690 (C++) // See Links section. %Y A352690 Cf. A000225, A353709, A353405. %K A352690 nonn,base,more %O A352690 0,3 %A A352690 _Rémy Sigrist_, May 15 2022