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 A100102 #12 Dec 01 2021 04:02:58
%S A100102 2,3,13,59,249,1015,4085,16371,65521,262127,1048557,4194283,16777193,
%T A100102 67108839,268435429,1073741795,4294967265,17179869151,68719476701,
%U A100102 274877906907,1099511627737,4398046511063,17592186044373,70368744177619,281474976710609,1125899906842575
%N A100102 a(n) = 2^(2*n)-(2*n-1).
%H A100102 Amiram Eldar, <a href="/A100102/b100102.txt">Table of n, a(n) for n = 0..1660</a>
%F A100102 a(n) = A000302(n) - A005408(n-1). - _Amiram Eldar_, Dec 01 2021
%p A100102 seq(2^(2*n)-(2*n-1),n=0..20);
%t A100102 Table[2^(2*n) - (2*n - 1), {n, 0, 25}] (* _Amiram Eldar_, Dec 01 2021 *)
%Y A100102 Cf. A000302, A005408, A119386.
%K A100102 nonn,easy
%O A100102 0,1
%A A100102 _Jorge Coveiro_, Dec 26 2004
%E A100102 More terms from _Emeric Deutsch_, Feb 15 2005