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A358902
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Number of integer compositions of n whose parts have weakly decreasing numbers of distinct prime factors (A001221).
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6
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1, 1, 2, 3, 5, 8, 13, 21, 33, 53, 84, 134, 213, 338, 536, 850, 1349, 2136, 3389, 5367, 8509, 13480, 21362, 33843, 53624, 84957, 134600, 213251, 337850, 535251, 847987, 1343440, 2128372, 3371895, 5341977, 8463051, 13407689, 21241181, 33651507, 53312538, 84460690
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OFFSET
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0,3
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LINKS
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EXAMPLE
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The a(0) = 1 through a(6) = 13 compositions:
() (1) (2) (3) (4) (5) (6)
(11) (21) (22) (23) (24)
(111) (31) (32) (33)
(211) (41) (42)
(1111) (221) (51)
(311) (222)
(2111) (231)
(11111) (321)
(411)
(2211)
(3111)
(21111)
(111111)
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MAPLE
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p:= proc(n) option remember; nops(ifactors(n)[2]) end:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<0, 0,
add((t-> `if`(t<=i, b(n-j, t), 0))(p(j)), j=1..n)))
end:
a:= n-> b(n$2):
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MATHEMATICA
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Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], GreaterEqual@@PrimeNu/@#&]], {n, 0, 10}]
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CROSSREFS
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The strictly decreasing case is A358903.
A116608 counts partitions by sum and number of distinct parts.
A334028 counts distinct parts in standard compositions.
A358836 counts multiset partitions with all distinct block sizes.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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