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A017838
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Expansion of 1/(1-x^5-x^6-x^7).
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1
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1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 2, 3, 2, 1, 1, 3, 6, 7, 6, 4, 5, 10, 16, 19, 17, 15, 19, 31, 45, 52, 51, 51, 65, 95, 128, 148, 154, 167, 211, 288, 371, 430, 469, 532, 666, 870, 1089, 1270, 1431, 1667, 2068, 2625, 3229
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OFFSET
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0,12
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COMMENTS
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Number of compositions (ordered partitions) of n into parts 5, 6 and 7. - Ilya Gutkovskiy, May 25 2017
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LINKS
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FORMULA
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a(n) = Sum_{k=0..floor(n/4)} Sum_{j=0..k} binomial(j,n-5*k-j)*binomial(k,j). - Vladimir Kruchinin, Nov 16 2011
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MAPLE
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seq(coeff(series(1/(1-x^5-x^6-x^7), x, n+1), x, n), n=0..60); # Muniru A Asiru, Jul 04 2018
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MATHEMATICA
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CoefficientList[Series[1/(1 - x^5 - x^6 - x^7), {x, 0, 60}], x] (* or *) LinearRecurrence[{0, 0, 0, 0, 1, 1, 1}, {1, 0, 0, 0, 0, 1, 1}, 60] (* Harvey P. Dale, Jun 28 2011 *)
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PROG
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(Maxima) a(n):=sum(sum(binomial(j, n-5*k-j)*binomial(k, j), j, 0, k), k, 0, n/4); /* Vladimir Kruchinin, Nov 16 2011 */
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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