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 A023557 #11 Jan 26 2023 10:05:18 %S A023557 0,1,1,2,4,6,10,16,27,43,70,113,183,297,480,777,1257,2034,3291,5326, %T A023557 8617,13943,22560,36503,59063,95566,154630,250196,404826,655022, %U A023557 1059848,1714870,2774718,4489588,7264307,11753895,19018202,30772097,49790299,80562396,130352695,210915091,341267786 %N A023557 Convolution of A023531 and Fibonacci numbers. %F A023557 a(n) = a(n-1)+a(n-2)+1 if n mod 4 = 0, else a(n) = a(n-1)+a(n-2), with offset 0. [_Gary Detlefs_, Dec 05 2010] %o A023557 (PARI) a(n) = sum(k=1, n, issquare(8*k+9)*fibonacci(n-k+1)); \\ _Michel Marcus_, Jan 26 2023 %Y A023557 Cf. A000045, A023531. %K A023557 nonn %O A023557 1,4 %A A023557 _Clark Kimberling_ %E A023557 More terms from _Michel Marcus_, Jan 26 2023