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 A181358 #14 Nov 26 2016 11:35:04 %S A181358 8,44,188,764,3068,12284,49148,196604,786428,3145724,12582908, %T A181358 50331644,201326588,805306364,3221225468,12884901884,51539607548, %U A181358 206158430204,824633720828,3298534883324,13194139533308,52776558133244,211106232532988,844424930131964 %N A181358 Number of twiddle factors in the first stage of a Pease Radix 4 Fast Fourier Transform. %C A181358 Number of twiddle factors in the first stage of a Pease Radix 4 Fast Fourier Transform. %H A181358 Colin Barker, <a href="/A181358/b181358.txt">Table of n, a(n) for n = 0..1000</a> %H A181358 Wikipedia, <a href="https://en.wikipedia.org/wiki/Twiddle_factor">Twiddle factor</a> %H A181358 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4). %F A181358 a(n) = 4*(3*4^n - 1). %F A181358 From _Colin Barker_, Nov 26 2016: (Start) %F A181358 a(n) = 4*A198693(n). %F A181358 a(n) = 5*a(n-1) - 4*a(n-2) for n>1. %F A181358 G.f.: 4*(2+x) / ((1-x) * (1-4*x)). %F A181358 (End) %o A181358 (PARI) Vec(4*(2+x) / ((1-x) * (1-4*x)) + O(x^30)) \\ _Colin Barker_, Nov 26 2016 %K A181358 nonn,easy %O A181358 0,1 %A A181358 Robert Koutsoyannis (bob.koutsoyannis(AT)gmail.com), Oct 14 2010