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A017828
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Expansion of 1/(1-x^4-x^5-x^6).
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1
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1, 0, 0, 0, 1, 1, 1, 0, 1, 2, 3, 2, 2, 3, 6, 7, 7, 7, 11, 16, 20, 21, 25, 34, 47, 57, 66, 80, 106, 138, 170, 203, 252, 324, 414, 511, 625, 779, 990, 1249, 1550, 1915, 2394, 3018, 3789, 4714, 5859, 7327, 9201, 11521
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,10
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..300
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FORMULA
| a(n) = a(n-6) + a(n-5) + a(n-4). - Jon Schoenfield (jonscho(AT)hiwaay.net), Aug 07 2006
a(n) = sum(k=0..n/3, sum(j=0..k, binomial(j,n-4*k-j)*binomial(k,j))). - Vladimir Kruchinin, Nov 16 2011
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MATHEMATICA
| LinearRecurrence[{0, 0, 0, 1, 1, 1}, {1, 0, 0, 0, 1, 1}, 60] (* Vincenzo Librandi, Nov 18 2011 *)
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PROG
| (Maxima) a(n):=sum(sum(binomial(j, n-4*k-j)*binomial(k, j), j, 0, k), k, 0, n/3); [From Vladimir Kruchinin, Nov 16 2011]
(MAGMA) I:=[1, 0, 0, 0, 1, 1]; [n le 6 select I[n] else Self(n-6)+Self(n-5)+Self(n-4): n in [1..60]]; // Vincenzo Librandi, Nov 18 2011
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CROSSREFS
| Sequence in context: A049879 A053812 A177865 * A140087 A174329 A160558
Adjacent sequences: A017825 A017826 A017827 * A017829 A017830 A017831
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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