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A003405
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G.f.: (1 + x^4 + x^7 + 2*x^8 + x^9 + x^12 + x^16)/Product_{i=1..8} (1 - x^i).
(Formerly M0754)
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4
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1, 1, 2, 3, 6, 8, 13, 19, 30, 41, 59, 80, 113, 149, 202, 264, 350, 447, 578, 730, 928, 1155, 1444, 1777, 2193, 2667, 3249, 3915, 4721, 5635, 6728, 7967, 9432, 11083, 13016, 15191, 17717, 20544, 23801, 27440, 31604, 36234, 41501, 47345, 53954, 61260, 69480, 78546, 88699
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OFFSET
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0,3
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COMMENTS
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Enumerates certain partially ordered sets of integers.
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REFERENCES
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J. C. P. Miller, On the enumeration of partially ordered sets of integers, pp. 109-124 of T. P. McDonough and V. C. Mavron, editors, Combinatorics: Proceedings of the Fourth British Combinatorial Conference 1973. London Mathematical Society, Lecture Note Series, Number 13, Cambridge University Press, NY, 1974. The g.f. is P(t) on page 122.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (1, 1, 0, 0, -1, 0, -1, 0, -1, 0, 1, 2, 1, 0, 1, -1, -1, -2, -1, -1, 1, 0, 1, 2, 1, 0, -1, 0, -1, 0, -1, 0, 0, 1, 1, -1).
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FORMULA
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a(n) = p(n,8) + p(n-4,8) + p(n-7,8) + 2*p(n-8,8) + p(n-9,8) + p(n-12,8) + p(n-16,8) where p(n,k) is the number of partitions of n into at most k parts. - Sean A. Irvine, Apr 22 2015
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MAPLE
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(1+x^4+x^7+2*x^8+x^9+x^12+x^16)/mul(1-x^i, i=1..8);
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MATHEMATICA
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CoefficientList[Series[(1+x^4+x^7+2x^8+x^9+x^12+x^16)/Product[1-x^i, {i, 8}], {x, 0, 50}], x] (* or *) LinearRecurrence[{1, 1, 0, 0, -1, 0, -1, 0, -1, 0, 1, 2, 1, 0, 1, -1, -1, -2, -1, -1, 1, 0, 1, 2, 1, 0, -1, 0, -1, 0, -1, 0, 0, 1, 1, -1}, {1, 1, 2, 3, 6, 8, 13, 19, 30, 41, 59, 80, 113, 149, 202, 264, 350, 447, 578, 730, 928, 1155, 1444, 1777, 2193, 2667, 3249, 3915, 4721, 5635, 6728, 7967, 9432, 11083, 13016, 15191}, 50] (* Harvey P. Dale, Jan 30 2024 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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