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 A340498 #11 Jan 11 2021 18:08:10 %S A340498 3,6,16,56,216,856,3416,13656,54616,218456,873816,3495256,13981016, %T A340498 55924056,223696216,894784856,3579139416,14316557656,57266230616, %U A340498 229064922456,916259689816 %N A340498 Where 2^n appears in A340488 for the first time. %C A340498 A subsequence of A340494 and A340497. Note that A340494 has a conjectured g.f. %H A340498 Rémy Sigrist, <a href="/A340498/a340498.txt">C program for A340498</a> %o A340498 (C) See Links section. %Y A340498 Cf. A340488, A340494-A340497. %K A340498 nonn,more %O A340498 0,1 %A A340498 _N. J. A. Sloane_, Jan 11 2021 %E A340498 a(8)-a(20) from _Rémy Sigrist_, Jan 11 2021