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A008672
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Expansion of 1/((1-x)*(1-x^3)*(1-x^5)).
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5
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1, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 17, 18, 20, 22, 23, 25, 27, 29, 31, 33, 35, 37, 40, 42, 44, 47, 49, 52, 55, 57, 60, 63, 66, 69, 72, 75, 78, 82, 85, 88, 92, 95, 99, 103, 106, 110, 114, 118, 122, 126, 130, 134, 139, 143, 147, 152, 156, 161, 166
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OFFSET
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0,4
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COMMENTS
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Number of partitions of n into odd parts less than or equal to 5.
1/((1-x^2)*(1-x^6)*(1-x^10)) is the Molien series for the icosahedral group [3,5] of order 120.
Number of partitions (d1,d2,d3) of n such that 0 <= d1/1 <= d2/2 <= d3/3. - Seiichi Manyama, Jun 04 2017
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REFERENCES
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L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 120, D(n;1,3,5).
W. Ebeling, Lattices and Codes, Vieweg; 2nd ed., 2002, see p. 164 etc.
F. Klein, Lectures on the Icosahedron ..., 2nd Rev. Ed., 1913; reprinted by Dover, NY, 1956; see pp. 236-243.
L. Smith, Polynomial Invariants of Finite Groups, Peters, 1995, p. 199 (No. 23).
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LINKS
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FORMULA
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a(n) = round((n+3)*(n+6)/30).
G.f.: 1/((1-x)*(1-x^3)*(1-x^5)).
a(n) = a(n-1) + a(n-3) - a(n-4) + a(n-5) - a(n-6) - a(n-8) + a(n-9); a(0)=1, a(1)=1, a(2)=1, a(3)=2, a(4)=2, a(5)=3, a(6)=4, a(7)=4, a(8)=5. - Harvey P. Dale, Feb 07 2012
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EXAMPLE
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G.f. = 1 + x + x^2 + 2*x^3 + 2*x^4 + 3*x^5 + 4*x^6 + 4*x^7 + 5*x^8 + 6*x^9 + 7*x^10 + ...
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MAPLE
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seq(coeff(series(1/((1-x)*(1-x^3)*(1-x^5)), x, n+1), x, n), n = 0..70); # G. C. Greubel, Sep 08 2019
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MATHEMATICA
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CoefficientList[Series[1/((1-x)(1-x^3)(1-x^5)), {x, 0, 70}], x] (* or *) LinearRecurrence[{1, 0, 1, -1, 1, -1, 0, -1, 1}, {1, 1, 1, 2, 2, 3, 4, 4, 5}, 70] (* Harvey P. Dale, Feb 07 2012 *)
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PROG
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(PARI) {a(n) = (n^2 + 9*n)\30 + 1} /* Michael Somos, Nov 25 2002 */
(Sage) [floor((n^2+9*n+30)/30) for n in (0..70)] # G. C. Greubel, Sep 08 2019
(GAP) List([0..70], n-> Int((n^2+9*n+30)/30) ); # G. C. Greubel, Sep 08 2019
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CROSSREFS
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KEYWORD
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nonn,nice,easy
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AUTHOR
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STATUS
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approved
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