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A079125
Number of ways to partition the sum of all divisors of n (sigma(n), A000203) into distinct positive integers not greater than n.
4
1, 1, 1, 2, 3, 5, 5, 13, 13, 27, 14, 89, 21, 89, 97, 230, 45, 613, 63, 980, 347, 580, 121, 6663, 330, 1289, 1043, 5847, 295, 26488, 389, 12813, 2800, 5411, 2840, 156304, 863, 10433, 6939, 161711, 1425, 272499, 1815, 103738, 61469, 35448, 2909, 2475011
OFFSET
1,4
FORMULA
a(n) = b(0, n), b(m, n) = 1 + sum(b(i, j): m<i<j<n & i+j=sigma(n)).
PROG
(PARI) a(n)=my(v=partitions(sigma(n), n)); sum(i=1, #v, #vecsort(v[i], , 8)==#v[i]) \\ Charles R Greathouse IV, Feb 14 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 27 2002
STATUS
approved