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A274502
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a(n) = 90*binomial(n-1,7) + 9*binomial(n-1,6).
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2
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0, 0, 9, 153, 972, 3996, 12690, 33858, 79596, 169884, 335907, 624195, 1101672, 1861704, 3031236, 4779108, 7325640, 10953576, 16020477, 22972653, 32360724, 44856900, 61274070, 82586790, 109954260, 144745380, 188565975, 243288279, 311082768, 394452432
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OFFSET
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5,3
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LINKS
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FORMULA
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G.f.: x^7*(9 + 81*x)/(1-x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>11.
a(n) = (n-1)*(n-2)*(n-3)*(n-4)*(n-5)*(n-6)*(10*n-63)/560. - Wesley Ivan Hurt, Jun 25 2016
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MAPLE
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MATHEMATICA
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Table[90 Binomial[n-1, 7] + 9 Binomial[n-1, 6], {n, 5, 40}]
LinearRecurrence[{8, -28, 56, -70, 56, -28, 8, -1}, {0, 0, 9, 153, 972, 3996, 12690, 33858}, 30] (* Harvey P. Dale, Nov 01 2019 *)
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PROG
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(Magma) [90*Binomial(n-1, 7) + 9*Binomial(n-1, 6): n in [5..40]];
(PARI) concat([0, 0], Vec(x^7*(9 + 81*x)/(1-x)^8 + O(x^100))) \\ Altug Alkan, Jun 26 2016
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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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