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A369804
Expansion of 1/(1 - x^3/(1-x)^5).
8
1, 0, 0, 1, 5, 15, 36, 80, 181, 431, 1060, 2617, 6401, 15521, 37513, 90741, 219918, 533619, 1295022, 3141826, 7619870, 18478155, 44810670, 108676262, 263576791, 639267800, 1550434777, 3760269946, 9119740067, 22118021213, 53642768716, 130099857234, 315531401964
OFFSET
0,5
COMMENTS
Number of compositions of 5*n-3 into parts 3 and 5.
FORMULA
a(n) = A052920(5*n-3) for n > 0.
a(n) = 5*a(n-1) - 10*a(n-2) + 11*a(n-3) - 5*a(n-4) + a(n-5) for n > 5.
a(n) = Sum_{k=0..floor(n/3)} binomial(n-1+2*k,n-3*k).
a(n) = A369845(n) - A369845(n-1). - R. J. Mathar, Feb 14 2024
PROG
(PARI) my(N=40, x='x+O('x^N)); Vec(1/(1-x^3/(1-x)^5))
(PARI) a(n) = sum(k=0, n\3, binomial(n-1+2*k, n-3*k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Feb 01 2024
STATUS
approved