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Number of partitions of n into proper divisors of n, cf. A027751.
10

%I #19 Oct 27 2023 19:54:31

%S 1,0,1,1,3,1,7,1,9,4,10,1,44,1,13,13,35,1,80,1,91,17,19,1,457,6,22,22,

%T 155,1,741,1,201,25,28,25,2233,1,31,29,1369,1,1653,1,336,285,37,1,

%U 9675,8,406,37,453,1,3131,37,3064,41,46,1,73154,1,49,492,1827

%N Number of partitions of n into proper divisors of n, cf. A027751.

%C For n > 0: a(A000040(n)) = 1 and a(A002808(n)) > 1.

%H Alois P. Heinz, <a href="/A210442/b210442.txt">Table of n, a(n) for n = 0..10000</a> (terms n = 0..197 from Reinhard Zumkeller)

%p with(numtheory):

%p a:= proc(n) local b, l; l:= sort([(divisors(n) minus {n})[]]):

%p b:= proc(m, i) option remember; `if`(m=0 or i=1, 1,

%p `if`(i<1, 0, b(m, i-1)+`if`(l[i]>m, 0, b(m-l[i], i))))

%p end; forget(b):

%p b(n, nops(l))

%p end:

%p seq(a(n), n=0..100); # _Alois P. Heinz_, Jan 29 2013

%t a[n_] := Module[{b, l}, l = Most[Divisors[n]]; b[m_, i_] := b[m, i] = If[m==0 || i==1, 1, If[i<1, 0, b[m, i-1] + If[l[[i]]>m, 0, b[m-l[[i]], i]]]]; b[n, Length[l]]]; a[0]=1; Table[a[n], {n, 0, 100}] (* _Jean-François Alcover_, Feb 02 2017, after _Alois P. Heinz_ *)

%o (Haskell)

%o a210442 n = p (a027751_row n) n where

%o p _ 0 = 1

%o p [] _ = 0

%o p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m

%Y Cf. A065205, A211110, A018818.

%K nonn,look

%O 0,5

%A _Reinhard Zumkeller_, Jan 21 2013

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Last modified September 22 11:31 EDT 2024. Contains 376114 sequences. (Running on oeis4.)