A121549 Number of ordered ways of writing n as a sum of two Fibonacci numbers (only one 1 is considered as a Fibonacci number).
0, 1, 2, 3, 2, 3, 2, 2, 2, 3, 2, 0, 2, 2, 2, 3, 0, 2, 0, 0, 2, 2, 2, 2, 0, 3, 0, 0, 2, 0, 0, 0, 0, 2, 2, 2, 2, 0, 2, 0, 0, 3, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0, 2, 0, 0, 2, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0
Offset: 1
Keywords
Examples
a(6)=3 because we have 6=1+5=3+3=5+1.
Links
- Alois P. Heinz, Table of n, a(n) for n = 1..10000
Programs
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Maple
with(combinat): g:=sum(z^fibonacci(i),i=2..30)^2: gser:=series(g,z=0,130): seq(coeff(gser,z,n),n=1..126);
Formula
G.f.: (Sum_{i>=2} x^Fibonacci(i))^2.
a(n) = A121548(n,2).