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A320804
Number of non-isomorphic multiset partitions of weight n with no singletons in which all parts are aperiodic multisets.
7
1, 0, 1, 2, 6, 13, 41, 104, 326, 958, 3096, 9958, 33869, 116806, 417741, 1526499, 5732931, 22015642, 86543717, 347495480, 1424832602, 5959123908, 25407212843, 110344848622, 487879651220, 2194697288628, 10039367091586, 46675057440634, 220447539120814
OFFSET
0,4
COMMENTS
Also the number of nonnegative integer matrices with (1) sum of elements equal to n, (2) no zero columns, (3) no rows summing to 0 or 1, and (4) no rows whose nonzero entries have a common divisor > 1, up to row and column permutations.
A multiset is aperiodic if its multiplicities are relatively prime.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
LINKS
EXAMPLE
Non-isomorphic representatives of the a(2) = 1 through a(5) = 13 multiset partitions with aperiodic parts and no singletons:
{{1,2}} {{1,2,2}} {{1,2,2,2}} {{1,1,2,2,2}}
{{1,2,3}} {{1,2,3,3}} {{1,2,2,2,2}}
{{1,2,3,4}} {{1,2,2,3,3}}
{{1,2},{1,2}} {{1,2,3,3,3}}
{{1,2},{3,4}} {{1,2,3,4,4}}
{{1,3},{2,3}} {{1,2,3,4,5}}
{{1,2},{1,2,2}}
{{1,2},{2,3,3}}
{{1,2},{3,4,4}}
{{1,2},{3,4,5}}
{{1,3},{2,3,3}}
{{1,4},{2,3,4}}
{{2,3},{1,2,3}}
PROG
(PARI)
EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
permcount(v) = {my(m=1, s=0, k=0, t); for(i=1, #v, t=v[i]; k=if(i>1&&t==v[i-1], k+1, 1); m*=t*k; s+=t); s!/m}
K(q, t, k)={EulerT(Vec(sum(j=1, #q, gcd(t, q[j])*x^lcm(t, q[j])) + O(x*x^k), -k))}
S(q, t, k)={Vec(sum(j=1, #q, if(t%q[j]==0, q[j]*x^t)) + O(x*x^k), -k)}
a(n)={if(n==0, 1, my(mbt=vector(n, d, moebius(d)), s=0); forpart(q=n, s+=permcount(q)*polcoef(exp(x*Ser(dirmul(mbt, sum(t=1, n, K(q, t, n)/t)) - sum(t=1, n, S(q, t, n)/t) )), n)); s/n!)} \\ Andrew Howroyd, Jan 16 2023
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 06 2018
EXTENSIONS
Terms a(11) and beyond from Andrew Howroyd, Jan 16 2023
STATUS
approved