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 A027151 #10 Oct 20 2019 07:09:04 %S A027151 1,3,7,21,45,135,291,873,1881,5643,12159,36477,78597,235791,508059, %T A027151 1524177,3284145,9852435,21229047,63687141,137226717,411680151, %U A027151 887047443,2661142329,5733964809,17201894427,37064931183,111194793549,239591481525,718774444575 %N A027151 a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A027144. %H A027151 Colin Barker, <a href="/A027151/b027151.txt">Table of n, a(n) for n = 0..1000</a> %H A027151 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,6,0,3). %F A027151 G.f.: (1 + 3*x)*(1 + x^2) / (1 - 6*x^2 - 3*x^4). %F A027151 a(n) = 6*a(n-2) + 3*a(n-4) for n>3. - _Colin Barker_, Jan 18 2018 %o A027151 (PARI) Vec((1 + 3*x)*(1 + x^2) / (1 - 6*x^2 - 3*x^4) + O(x^40)) \\ _Colin Barker_, Jan 18 2018 %Y A027151 Cf. A141041 (bisection), A287811 (bisection). %K A027151 nonn,easy %O A027151 0,2 %A A027151 _Clark Kimberling_