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 A108479 #26 Mar 29 2025 04:27:58
%S A108479 1,1,2,7,17,44,117,305,798,2091,5473,14328,37513,98209,257114,673135,
%T A108479 1762289,4613732,12078909,31622993,82790070,216747219,567451585,
%U A108479 1485607536,3889371025,10182505537,26658145586,69791931223,182717648081
%N A108479 Antidiagonal sums of number triangle A086645.
%H A108479 Seiichi Manyama, <a href="/A108479/b108479.txt">Table of n, a(n) for n = 0..5000</a>
%H A108479 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,2,-1).
%F A108479 G.f.: (1 - x - x^2)/(1 - 2*x - x^2 - 2*x^3 + x^4).
%F A108479 a(n) = 2*(n-1) + a(n-2) + 2*a(n-3) - a(n-4).
%F A108479 a(n) = Sum_{k=0..floor(n/2)} C(2*(n-k), 2*k).
%F A108479 a(n) = Sum_{k=0..floor(n/2)} Sum_{j=0..n-k} C(2*(n-2*k), j) * C(2*k, j).
%F A108479 a(n) = A005252(2*n). - _Seiichi Manyama_, Aug 11 2024
%t A108479 LinearRecurrence[{2,1,2,-1},{1,1,2,7},30] (* _Harvey P. Dale_, Jun 01 2021 *)
%Y A108479 Cf. A005252, A051286, A086645, A182890.
%Y A108479 Cf. A381421, A382230, A382470, A382471, A382472, A382473, A382474.
%Y A108479 Cf. A376729, A376730, A376731.
%K A108479 easy,nonn
%O A108479 0,3
%A A108479 _Paul Barry_, Jun 04 2005