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A097950
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G.f.: (1+x^5+x^10)/((1-x)*(1-x^3)).
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0
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1, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72
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OFFSET
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0,4
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LINKS
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E. M. Rains and N. J. A. Sloane, Self-dual codes, pp. 177-294 of Handbook of Coding Theory, Elsevier, 1998 (Abstract, pdf, ps).
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FORMULA
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Molien series is (1+x^10+x^20)/((1-x^2)*(1-x^6)).
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MATHEMATICA
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CoefficientList[Series[(1+x^5+x^10)/((1-x)*(1-x^3)), {x, 0, 80}], x] (* or *) LinearRecurrence[{2, -1}, {1, 1, 1, 2, 2, 3, 4, 4, 5}, 80] (* Harvey P. Dale, Oct 11 2015 *)
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PROG
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(PARI) a(n)=if(n>7, n-3, [1, 1, 1, 2, 2, 3, 4, 4][n+1]) \\ Charles R Greathouse IV, Oct 27 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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