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A181887 a(0) = 0, and for n > 0, a(n) = A002956(n) - A000041(n) 0

%I #10 Mar 30 2012 17:23:31

%S 0,0,0,1,2,8,9,33,43,89,124,292,290,726,839,1318,1904,3616,3653,7446,

%T 7620,12175,16474,27907,26490,47651,56922,80410,93525,160402,146944,

%U 273510,286942,395776,495852,659747,690842

%N a(0) = 0, and for n > 0, a(n) = A002956(n) - A000041(n)

%C A002956 can be thought of as a modular arithmetic version of the partition numbers (A000041). The number of "modulo n" partitions of n is the number of multisets of integers ranging from 1 to n, such that the sum of members of the multiset is congruent to 0 mod n, and no submultiset exists whose members sum to 0 mod n. Therefore, a(n) is the number of "modulo n" partitions which are not ordinary partitions of n.

%H Finklea, Moore, Ponomarenko and Turner, <a href="http://www-rohan.sdsu.edu/~vadim/fmpt1b-revised.pdf">Invariant Polynomials and Minimal Zero Sequences</a>

%e The multisets counted by A002956(5) but not by A000041(5) are

%e ..{1,3,3,3}

%e ..{2,2,2,2,2}

%e ..{2,2,2,4}

%e ..{2,4,4}

%e ..{3,3,3,3,3}

%e ..{3,4,4,4}

%e ..{3,3,4}

%e ..{4,4,4,4,4}

%e So a(5) = 8.

%Y Cf. A000041, A002956, A082641

%K nonn

%O 0,5

%A _Andrew Weimholt_, Feb 01 2011

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