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A145513
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Number of partitions of 10^n into powers of 10.
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6
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1, 2, 12, 562, 195812, 515009562, 10837901390812, 1899421190329234562, 2851206628197445401265812, 37421114946843687272702534859562, 4362395890943439751990308572939648140812, 4573514084633441973328831327010967245403925484562, 43557001521047571730475817291330175020887917015964570015812
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = [x^(10^n)] 1/Product_{j>=0} (1-x^(10^j)).
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EXAMPLE
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a(1) = 2, because there are 2 partitions of 10^1 into powers of 10: [1,1,1,1,1,1,1,1,1,1], [10].
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MAPLE
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g:= proc(b, n, k) option remember; local t; if b<0 then 0 elif b=0 or n=0 or k<=1 then 1 elif b>=n then add(g(b-t, n, k) *binomial(n+1, t) *(-1)^(t+1), t=1..n+1); else g(b-1, n, k) +g(b*k, n-1, k) fi end: a:= n-> g(1, n, 10): seq(a(n), n=0..13);
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MATHEMATICA
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g[b_, n_, k_] := g[b, n, k] = Module[{t}, Which[b < 0, 0, b == 0 || n == 0 || k <= 1, 1, b >= n, Sum[g[b - t, n, k]*Binomial[n + 1, t] *(-1)^(t + 1), {t, 1, n + 1}], True, g[b - 1, n, k] + g[b*k, n - 1, k]]]; a[n_] := g[1, n, 10]; Table[a[n], {n, 0, 13}] (* Jean-François Alcover, Feb 01 2017, after Alois P. Heinz *)
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PROG
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(Haskell)
import Data.MemoCombinators (memo2, list, integral)
a145513 n = a145513_list !! n
a145513_list = f [1] where
f xs = (p' xs $ last xs) : f (1 : map (* 10) xs)
p' = memo2 (list integral) integral p
p _ 0 = 1; p [] _ = 0
p ks'@(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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nonn
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AUTHOR
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STATUS
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approved
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