%I #6 Nov 07 2024 20:40:41

%S 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 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 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 Triangle read by rows: the triangle in A108035 surrounded by a border of 0's.

%F G.f.: x*y*(1+x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates]

%e 0; 0,0; 0,1,0; 0,2,2,0; 0,3,3,3,0; 0,5,5,5,5,0; ...

%o (Python)

%o from math import isqrt

%o from sympy import fibonacci

%o 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 Cf. A039913, A108035.

%K nonn,tabl

%O 0,8

%A _N. J. A. Sloane_, Jun 01 2005