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A369816
Expansion of 1/(1 - x^5 - x^7).
5
1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 2, 0, 1, 1, 0, 3, 0, 3, 1, 1, 4, 0, 6, 1, 4, 5, 1, 10, 1, 10, 6, 5, 15, 2, 20, 7, 15, 21, 7, 35, 9, 35, 28, 22, 56, 16, 70, 37, 57, 84, 38, 126, 53, 127, 121, 95, 210, 91, 253, 174, 222, 331, 186, 463, 265, 475, 505, 408, 794, 451, 938, 770, 883, 1299, 859, 1732, 1221
OFFSET
0,13
COMMENTS
Number of compositions of n into parts 5 and 7.
FORMULA
a(n) = a(n-5) + a(n-7).
Gf.: 1/((1-x+x^2)*(1+x-x^3-x^4-x^5)) . - R. J. Mathar, Jul 03 2024
PROG
(PARI) my(N=80, x='x+O('x^N)); Vec(1/(1-x^5-x^7))
(PARI) a(n) = sum(k=0, n\7, ((n-2*k)%5==0)*binomial((n-2*k)/5, k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Feb 02 2024
STATUS
approved