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A097333
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a(n) = Sum_{k=0..n} C(n-k, floor(k/2)).
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19
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1, 2, 2, 3, 5, 7, 10, 15, 22, 32, 47, 69, 101, 148, 217, 318, 466, 683, 1001, 1467, 2150, 3151, 4618, 6768, 9919, 14537, 21305, 31224, 45761, 67066, 98290, 144051, 211117, 309407, 453458, 664575, 973982, 1427440, 2092015, 3065997, 4493437, 6585452
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: (1+x-x^2-x^3)/((1-x)*(1-x^2-x^3-x^4)) = (1+x)/(1-x-x^3);
a(n) = a(n-1) + a(n-3);
a(n) = a(n-1) + a(n-2) - a(n-5).
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MATHEMATICA
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PROG
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(PARI) a(n) = sum(k=0, n, binomial(n-k, k\2)); \\ Michel Marcus, Mar 02 2022
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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