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A108036
Triangle read by rows: the triangle in A108035 surrounded by a border of 0's.
3
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, 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, 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
OFFSET
0,8
FORMULA
G.f.: x*y*(1+x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates]
EXAMPLE
0; 0,0; 0,1,0; 0,2,2,0; 0,3,3,3,0; 0,5,5,5,5,0; ...
PROG
(Python)
from math import isqrt
from sympy import fibonacci
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
CROSSREFS
Sequence in context: A128540 A160692 A051775 * A190174 A263139 A063711
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Jun 01 2005
STATUS
approved