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 A193475 #10 Jun 30 2023 18:44:55 %S A193475 2,56,992,16256,261632,4192256,67100672,1073709056,17179738112, %T A193475 274877382656,4398044413952,70368735789056,1125899873288192, %U A193475 18014398375264256,288230375614840832,4611686016279904256,73786976286248271872,1180591620683051565056 %N A193475 a(n) = 4*16^n - 2*4^n. %H A193475 Peter Luschny, <a href="http://oeis.org/wiki/User:Peter_Luschny/TheLostBernoulliNumbers">The lost Bernoulli numbers.</a> %H A193475 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (20, -64). %F A193475 Recurrence: a(0) = 2, a(1) = 56, a(n) = 20*a(n-1) - 64*a(n-2). %F A193475 G.f.: (16*x+2)/(64*x^2-20*x+1). %F A193475 E.g.f.: 4*exp(16*x) - 2*exp(4*x). %p A193475 A193475 := proc(n) 2^(2*n+1); %^2; % - %% end: seq (A193475(n), n=0..20); %K A193475 nonn %O A193475 0,1 %A A193475 Peter Luschny, Aug 07 2011