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 A090411 #28 Mar 25 2025 20:40:53
%S A090411 1,15,240,3840,61440,983040,15728640,251658240,4026531840,64424509440,
%T A090411 1030792151040,16492674416640,263882790666240,4222124650659840,
%U A090411 67553994410557440,1080863910568919040,17293822569102704640,276701161105643274240,4427218577690292387840
%N A090411 Expansion of g.f. (1-x)/(1-16*x).
%H A090411 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (16).
%F A090411 a(n) = 15*16^(n-1) + 0^n/16.
%F A090411 a(n) = Sum_{j=0..3, Sum_{k=0..n, C(4*n+j, 4*k)}}.
%F A090411 a(n) = (A070775(n) + A090407(n) + A001025(n) + A090408(n))/4.
%F A090411 From _Elmo R. Oliveira_, Mar 25 2025: (Start)
%F A090411 E.g.f.: (15*exp(16*x) + 1)/16.
%F A090411 a(n) = 16*a(n-1) for n > 1. (End)
%t A090411 Join[{1, a = 15}, Table[a=16*a, {n,0,30}]] (* _Vladimir Joseph Stephan Orlovsky_, Jun 10 2011 *)
%t A090411 Join[{1},NestList[16#&,15,20]] (* _Harvey P. Dale_, Dec 28 2016 *)
%o A090411 (PARI) a(n)=if(n,15<<(4*n-4),1) \\ _Charles R Greathouse IV_, Jun 10 2011
%Y A090411 Cf. A001025, A070775, A090407, A090408, A090409.
%K A090411 easy,nonn
%O A090411 0,2
%A A090411 _Paul Barry_, Nov 30 2003