

A121550


Number of ordered ways of writing n as a sum of three Fibonacci numbers (only one 1 is considered as a Fibonacci number).


3



0, 0, 1, 3, 6, 7, 9, 9, 10, 9, 12, 12, 9, 9, 10, 12, 12, 12, 12, 6, 9, 6, 12, 13, 9, 12, 12, 9, 12, 6, 12, 6, 0, 9, 6, 9, 15, 9, 13, 9, 6, 12, 9, 12, 9, 0, 12, 6, 6, 12, 0, 6, 0, 0, 9, 6, 9, 12, 9, 15, 9, 6, 13, 6, 9, 6, 0, 12, 9, 9, 12, 0, 9, 0, 0, 12, 6, 6, 6, 0, 12, 0, 0, 6, 0, 0, 0, 0, 9, 6, 9, 12
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OFFSET

1,4


COMMENTS

a(n)=A121548(n,3).


LINKS

Table of n, a(n) for n=1..92.


FORMULA

G.f.=sum(z^fibonacci(i), i = 2..infinity)^3.


EXAMPLE

a(6)=7 because we have 6=1+2+3=1+3+2=2+1+3=2+3+1=3+1+2=3+2+1=2+2+2.


MAPLE

with(combinat): g:=sum(z^fibonacci(i), i=2..30)^3: gser:=series(g, z=0, 130): seq(coeff(gser, z, n), n=1..126);


CROSSREFS

Cf. A000045, A121548, A121549.
Sequence in context: A181911 A181919 A021735 * A067751 A283762 A088045
Adjacent sequences: A121547 A121548 A121549 * A121551 A121552 A121553


KEYWORD

nonn


AUTHOR

Emeric Deutsch, Aug 07 2006


STATUS

approved



