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A272691
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Number of factorizations of the highly factorable numbers A033833.
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3
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1, 2, 3, 4, 5, 7, 9, 12, 16, 19, 21, 29, 30, 31, 38, 47, 52, 57, 64, 77, 98, 105, 109, 118, 171, 212, 289, 382, 392, 467, 484, 662, 719, 737, 783, 843, 907, 1097, 1261, 1386, 1397, 1713, 1768, 2116, 2179, 2343, 3079, 3444, 3681, 3930, 5288, 5413, 5447
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OFFSET
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1,2
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COMMENTS
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These are defined as record numbers of factorizations (A001055). - Gus Wiseman, Jan 13 2020
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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(8) = 12 factorizations of highly factorable numbers:
() (4) (8) (12) (16) (24) (36) (48)
(2*2) (2*4) (2*6) (2*8) (3*8) (4*9) (6*8)
(2*2*2) (3*4) (4*4) (4*6) (6*6) (2*24)
(2*2*3) (2*2*4) (2*12) (2*18) (3*16)
(2*2*2*2) (2*2*6) (3*12) (4*12)
(2*3*4) (2*2*9) (2*3*8)
(2*2*2*3) (2*3*6) (2*4*6)
(3*3*4) (3*4*4)
(2*2*3*3) (2*2*12)
(2*2*2*6)
(2*2*3*4)
(2*2*2*2*3)
(End)
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MATHEMATICA
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facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Table[Length[facs[n]], {n, 100}]//.{foe___, x_, y_, afe___}/; x>=y:>{foe, x, afe} (* Gus Wiseman, Jan 13 2020 *)
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CROSSREFS
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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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