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 A099603 #16 Feb 05 2025 22:03:12
%S A099603 1,2,4,12,20,64,104,336,544,1760,2848,9216,14912,48256,78080,252672,
%T A099603 408832,1323008,2140672,6927360,11208704,36272128,58689536,189923328,
%U A099603 307302400,994451456,1609056256,5207015424,8425127936,27264286720,44114542592,142757658624,230986743808
%N A099603 Row sums of triangle A099602, in which row n equals the inverse binomial transform of column n of the triangle of trinomial coefficients (A027907).
%H A099603 Stefano Spezia, <a href="/A099603/b099603.txt">Table of n, a(n) for n = 0..2500</a>
%H A099603 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,6,0,-4).
%F A099603 a(n) = Fibonacci(n+1)*2^((n+1)/2).
%F A099603 a(n) = 6*a(n-2) - 4*a(n-4) for n>4.
%F A099603 G.f.: (1+2*x-2*x^2)/(1-6*x^2+4*x^4).
%e A099603 Sequence begins: {1*1, 1*2, 2*2, 3*4, 5*4, 8*8, 13*8, 21*16, 34*16, ...}.
%t A099603 LinearRecurrence[{0,6,0,-4},{1,2,4,12},30] (* _Harvey P. Dale_, Aug 09 2016 *)
%o A099603 (PARI) a(n)=fibonacci(n+1)*2^((n+1)\2)
%Y A099603 Cf. A000045, A027907, A099602.
%K A099603 nonn,easy
%O A099603 0,2
%A A099603 _Paul D. Hanna_, Oct 25 2004