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A264997
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Number of partitions of n into distinct parts of the form 3^a*5^b.
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3
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1, 1, 0, 1, 1, 1, 1, 0, 1, 2, 1, 0, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 0, 1, 2, 2, 1, 2, 3, 2, 3, 2, 2, 3, 2, 2, 2, 2, 1, 2, 3, 2, 3, 3, 2, 4, 3, 1, 3, 3, 3, 3, 3, 3, 4, 4, 2, 4, 3, 2, 4, 3, 2, 2, 2, 2, 2, 2, 2, 3, 4, 2, 3, 4, 2, 5, 5, 3, 4, 4, 4, 5, 4, 2, 6, 6, 3, 5
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OFFSET
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0,10
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LINKS
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FORMULA
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G.f.: (1+x)(1+x^3)(1+x^5)(1+x^9)(1+x^15)....
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EXAMPLE
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28 = 27 + 1 = 25 + 3 = 15 + 9 + 3 + 1, so a(28) = 3.
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MATHEMATICA
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nmax = 100; A003593 = Select[Range[nmax], PowerMod[15, #, #] == 0 &]; CoefficientList[Series[Product[(1 + x^(A003593[[k]])), {k, 1, Length[A003593]}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 01 2015 *)
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PROG
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(Haskell)
import Data.MemoCombinators (memo2, list, integral)
a264997 n = a264997_list !! (n-1)
a264997_list = f 0 [] a003593_list where
f u vs ws'@(w:ws) | u < w = (p' vs u) : f (u + 1) vs ws'
| otherwise = f u (vs ++ [w]) ws
p' = memo2 (list integral) integral p
p _ 0 = 1
p [] _ = 0
p (k:ks) m = if m < k then 0 else p' ks (m - k) + p' ks m
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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