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A017838
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Expansion of 1/(1-x^5-x^6-x^7).
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0
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,12
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FORMULA
| a(n) = a(n-5) + a(n-6) + a(n-7). - Vincenzo Librandi, Mar 23 2011
a(n) = sum(k=0..n/4, sum(j=0..k, binomial(j,n-5*k-j)*binomial(k,j))). -Vladimir Kruchinin, nov 16 2011
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MATHEMATICA
| 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] (* From Harvey P. Dale, June 28 2011 *)
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PROG
| (Maxima) a(n):=sum(sum(binomial(j, n-5*k-j)*binomial(k, j), j, 0, k), k, 0, n/4); [From Vladimir Kruchinin, nov 16 2011]
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CROSSREFS
| Sequence in context: A086437 A027907 A026323 * A181567 A058294 A082868
Adjacent sequences: A017835 A017836 A017837 * A017839 A017840 A017841
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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