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A317141
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In the ranked poset of integer partitions ordered by refinement, number of integer partitions coarser (greater) than or equal to the integer partition with Heinz number n.
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14
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1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 4, 1, 2, 2, 5, 1, 4, 1, 4, 2, 2, 1, 6, 2, 2, 3, 4, 1, 5, 1, 7, 2, 2, 2, 8, 1, 2, 2, 7, 1, 5, 1, 4, 4, 2, 1, 10, 2, 4, 2, 4, 1, 7, 2, 7, 2, 2, 1, 9, 1, 2, 4, 11, 2, 5, 1, 4, 2, 5, 1, 12, 1, 2, 4, 4, 2, 5, 1, 11, 5, 2, 1, 10, 2
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OFFSET
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1,4
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COMMENTS
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The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
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LINKS
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EXAMPLE
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The a(24) = 6 partitions coarser than or equal to (2111) are (2111), (311), (221), (32), (41), (5), with Heinz numbers 24, 20, 18, 15, 14, 11.
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MAPLE
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g:= l-> `if`(l=[], {[]}, (t-> map(sort, map(x->
[seq(subsop(i=x[i]+t, x), i=1..nops(x)),
[x[], t]][], g(subsop(-1=[][], l)))))(l[-1])):
a:= n-> nops(g(map(i-> numtheory[pi](i[1])$i[2], ifactors(n)[2]))):
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MATHEMATICA
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primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
sps[{}]:={{}}; sps[set:{i_, ___}]:=Join@@Function[s, Prepend[#, s]&/@sps[Complement[set, s]]]/@Cases[Subsets[set], {i, ___}];
mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
ptncaps[ptn_]:=Union[Sort/@Apply[Plus, mps[ptn], {2}]];
Table[Length[ptncaps[primeMS[n]]], {n, 100}]
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CROSSREFS
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Cf. A002846, A056239, A213427, A215366, A265947, A296150, A296150, A299201, A300383, A317142, A317143.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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