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A256433
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Characteristic function of dodecahedral numbers.
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2
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1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
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OFFSET
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0
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COMMENTS
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Dodecahedral numbers are of the form m(3m-1)(3m-2)/2.
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LINKS
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FORMULA
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For n > 0, a(n) = floor(t(n) + 1/(27 * t(n)) + 1/3) - floor(t(n-1) + 1/(27 * t(n-1)) + 1/3), where t(n) = ( sqrt(243*n^2-1)/(3^(9/2)) + n/9 )^(1/3).
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MATHEMATICA
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With[{ddn=Table[m(3m-1)(3m-2)/2, {m, 0, 10}]}, Table[If[MemberQ[ddn, n], 1, 0], {n, 0, 100}]] (* Harvey P. Dale, Oct 18 2015 *)
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PROG
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(PARI)
A006566(n) = (n*(3*n-1)*(3*n-2)/2);
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CROSSREFS
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Cf. A006566 (dodecahedral numbers).
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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