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 A108036 #6 Nov 07 2024 20:40:41 %S A108036 0,0,0,0,1,0,0,2,2,0,0,3,3,3,0,0,5,5,5,5,0,0,8,8,8,8,8,0,0,13,13,13, %T A108036 13,13,13,0,0,21,21,21,21,21,21,21,0,0,34,34,34,34,34,34,34,34,0,0,55, %U A108036 55,55,55,55,55,55,55,55,0,0,89,89,89,89,89,89,89,89,89,89,0,0,144,144,144,144 %N A108036 Triangle read by rows: the triangle in A108035 surrounded by a border of 0's. %F A108036 G.f.: x*y*(1+x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates] %e A108036 0; 0,0; 0,1,0; 0,2,2,0; 0,3,3,3,0; 0,5,5,5,5,0; ... %o A108036 (Python) %o A108036 from math import isqrt %o A108036 from sympy import fibonacci %o A108036 def A108036(n): return 0 if 0<=(k:=n+1<<1)-(r:=(m:=isqrt(k))*(m+1))<=2 or n<=1 else int(fibonacci(m-(k<=r))) # _Chai Wah Wu_, Nov 07 2024 %Y A108036 Cf. A039913, A108035. %K A108036 nonn,tabl %O A108036 0,8 %A A108036 _N. J. A. Sloane_, Jun 01 2005