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 A073995 #16 May 03 2019 07:17:44 %S A073995 1,1,7,28,76,256,1072,4288,16576,65536,262912,1051648,4197376, %T A073995 16777216,67121152,268484608,1073790976,4294967296,17180065792, %U A073995 68720263168,274878693376,1099511627776,4398049656832,17592198627328,70368756760576,281474976710656,1125899957174272,4503599828697088,18014398710808576 %N A073995 Number of strings of length n over GF(4) with trace 0 and subtrace 0. %H A073995 F. Ruskey <a href="http://combos.org/TSstringF4">Strings over GF(4) with given trace and subtrace</a> %F A073995 a(n; t, s) = a(n-1; t, s) + a(n-1; t-1, s-(t-1)) + a(n-1; t-2, s-2(t-2)) + a(n-1; t-3, s-3(t-3)) where t is the trace and s is the subtrace. Note that all operations involving operands t or s are carried out over GF(4). %F A073995 G.f.: -q*(26*q^3+5*q-1-13*q^2)/[(1-2q)(1-4q)(1+4q^2)]. - Lawrence Sze, Oct 24 2004 %Y A073995 Cf. A073996, A073997, A073998, A073999, A074000. %K A073995 easy,nonn %O A073995 1,3 %A A073995 _Frank Ruskey_ and Nate Kube, Aug 16 2002 %E A073995 More terms from _Max Alekseyev_, Apr 16 2013