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A098743
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Number of partitions of n into aliquant parts (i.e., parts that do not divide n).
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31
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1, 0, 0, 0, 0, 1, 0, 3, 1, 3, 3, 13, 1, 23, 10, 11, 9, 65, 8, 104, 14, 56, 66, 252, 10, 245, 147, 206, 77, 846, 35, 1237, 166, 649, 634, 1078, 60, 3659, 1244, 1850, 236, 7244, 299, 10086, 1228, 1858, 4421, 19195, 243, 17660, 3244, 12268, 4039, 48341, 1819, 27675
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OFFSET
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0,8
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COMMENTS
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It seems very plausible that the low and high water marks occur when n is a factorial number or a prime: see A260797, A260798.
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LINKS
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EXAMPLE
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7 = 2 + 2 + 3 = 2 + 5 = 3 + 4, so a(7) = 3.
a(10) = #{7+3,6+4,4+3+3} = 3, all other partitions of 10 contain at least one divisor (10, 5, 2, or 1).
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MAPLE
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a := [1, 0, 0, 0, 0]; M:=300; for n from 5 to M do t1:={seq(i, i=1..n)}; t3 := t1 minus divisors(n); t4 := mul(1/(1-x^i), i in t3); t5 := series(t4, x, n+2); a:=[op(a), coeff(t5, x, n)]; od: a; # N. J. A. Sloane, Aug 08 2015
# second Maple program:
a:= proc(m) option remember; local b; b:= proc(n, i)
option remember; `if`(n=0, 1, `if`(i<2, 0, b(n, i-1)+
`if`(irem(m, i)=0, 0, b(n-i, min(i, n-i))))) end; b(m$2)
end:
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MATHEMATICA
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a[m_] := a[m] = Module[{b}, b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 2, 0, b[n, i-1] + If[Mod[m, i] == 0, 0, b[n-i, Min[i, n-i]]]]]; b[m, m]];
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PROG
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(Haskell)
a098743 n = p [nd | nd <- [1..n], mod n nd /= 0] n where
p _ 0 = 1
p [] _ = 0
p ks'@(k:ks) m | m < k = 0 | otherwise = p ks' (m - k) + p ks m
(Haskell) -- with memoization
import Data.MemoCombinators (memo3, integral)
a098743 n = a098743_list !! n
a098743_list = map (\x -> pMemo x 1 x) [0..] where
pMemo = memo3 integral integral integral p
p _ _ 0 = 1
p x k m | m < k = 0
| mod x k == 0 = pMemo x (k + 1) m
| otherwise = pMemo x k (m - k) + pMemo x (k + 1) m
(PARI) a(n)={polcoef(1/prod(k=1, n, if(n%k, 1 - x^k, 1) + O(x*x^n)), n)} \\ Andrew Howroyd, Aug 29 2018
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CROSSREFS
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See also A057562 (relatively prime parts).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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New wording for definition suggested by Marc LeBrun, Aug 07 2015
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STATUS
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approved
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