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 A087431 #15 Jan 02 2021 12:35:46
%S A087431 1,2,8,28,88,256,704,1856,4736,11776,28672,68608,161792,376832,868352,
%T A087431 1982464,4489216,10092544,22544384,50069504,110624768,243269632,
%U A087431 532676608,1161822208,2524971008,5469372416,11811160064,25434259456
%N A087431 a(n) = 0^n/2 + 2^n*(n^2+n+2)/4.
%C A087431 Binomial transform of A080335 (with additional leading 1).
%H A087431 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-12,8).
%F A087431 a(n) = 2*A007466(n) for n >= 1.
%F A087431 G.f.: (1-4*x+8*x^2-4*x^3)/(1-2*x)^3. - _Colin Barker_, Mar 18 2012
%t A087431 LinearRecurrence[{6,-12,8},{1,2,8,28},30] (* _Harvey P. Dale_, Nov 26 2015 *)
%K A087431 easy,nonn
%O A087431 0,2
%A A087431 _Paul Barry_, Sep 02 2003