OFFSET
0,7
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: (-x^12-x^9+2*x^6+x^3-1) / (x^19 -x^18 -x^16 -x^15 -2*x^13 -7*x^12 +x^10 -8*x^9 +x^7 +9*x^6 +x^3-1).
EXAMPLE
a(10) = 2:
._._._._._._._._._._. ._._._._._._._._._._.
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| | | |___|___|___|___|___|
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|_________|_________| | | |
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|___|___|___|___|___| |_________|_________|
MAPLE
a:= n-> coeff(series((-x^12-x^9+2*x^6+x^3-1) / (x^19 -x^18 -x^16 -x^15 -2*x^13 -7*x^12 +x^10 -8*x^9 +x^7 +9*x^6 +x^3-1), x, n+1), x, n):
seq(a(n), n=0..70);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Jun 05 2013
STATUS
approved