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A007360
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Number of partitions of n into distinct and pairwise relatively prime parts.
(Formerly M0264)
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47
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1, 1, 2, 2, 3, 3, 4, 5, 5, 6, 8, 9, 10, 11, 10, 13, 17, 19, 21, 22, 21, 24, 32, 37, 37, 38, 40, 45, 55, 65, 69, 66, 64, 75, 86, 100, 113, 107, 106, 122, 145, 165, 174, 167, 162, 179, 222, 253, 255, 255, 255, 273, 328, 373, 376, 369, 377, 406, 476, 553, 569, 537, 529
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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EXAMPLE
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The a(1) = 1 through a(10) = 6 partitions (A = 10):
(1) (2) (3) (4) (5) (6) (7) (8) (9) (A)
(21) (31) (32) (51) (43) (53) (54) (73)
(41) (321) (52) (71) (72) (91)
(61) (431) (81) (532)
(521) (531) (541)
(721)
(End)
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MATHEMATICA
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$RecursionLimit = 1000; b[n_, i_, s_] := b[n, i, s] = Module[{f}, If[n == 0 || i == 1, 1, If[i<2, 0, f = FactorInteger[i][[All, 1]]; b[n, i-1, Select[s, #<i&]] + If[i <= n && f ~Intersection~ s == {}, b[n-i, i-1, Select[s ~Union~ f, #<i&]], 0]]]]; a[n_] := b[n, n, {}] - b[n-2, n-2, {}]; Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Mar 20 2014, after Alois P. Heinz *)
Table[Length[Select[IntegerPartitions[n], Length[#]==1||UnsameQ@@#&&CoprimeQ@@Union[#]&]], {n, 0, 30}] (* Gus Wiseman, Sep 23 2019 *)
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CROSSREFS
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Number of partitions of n into relatively prime parts = A000837.
Strict relatively prime partitions are A078374.
Cf. A007359, A038348, A084422, A186974, A187106, A303140, A302569, A303362, A304714, A320426, A320436.
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 13 2005
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STATUS
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approved
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