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Search: id:A027746
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| A027746 |
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Triangle in which first row is 1, n-th row (n>1) gives prime factors of n with repetition. |
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+0
9
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| 1, 2, 3, 2, 2, 5, 2, 3, 7, 2, 2, 2, 3, 3, 2, 5, 11, 2, 2, 3, 13, 2, 7, 3, 5, 2, 2, 2, 2, 17, 2, 3, 3, 19, 2, 2, 5, 3, 7, 2, 11, 23, 2, 2, 2, 3, 5, 5, 2, 13, 3, 3, 3, 2, 2, 7, 29, 2, 3, 5, 31, 2, 2, 2, 2, 2, 3, 11, 2, 17, 5, 7, 2, 2, 3, 3, 37, 2, 19, 3, 13, 2, 2, 2, 5, 41, 2, 3, 7, 43, 2, 2, 11, 3, 3, 5
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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n-th row has length A001222(n) (n>1).
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LINKS
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N. J. A. Sloane, First 2048 rows of triangle, flattened
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EXAMPLE
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1; 2; 3; 2,2; 5; 2,3; 7; 2,2,2; 3,3; 2,5; ...
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MAPLE
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P:=proc(n) local FM: FM:=ifactors(n)[2]: seq(seq(FM[j][1], k=1..FM[j][2]), j=1..nops(FM)) end: 1; for n from 2 to 45 do P(n) od; # yields sequence in triangular form (Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 13 2005)
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CROSSREFS
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Cf. A000027, A001222, A027748.
a(A022559(A000040(n))+1) = A000040(n).
Sequence in context: A029247 A053269 A118665 this_sequence A128651 A093797 A119809
Adjacent sequences: A027743 A027744 A027745 this_sequence A027747 A027748 A027749
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KEYWORD
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nonn,easy,nice,tabf
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AUTHOR
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MAGHRAOUI Abdelkader (maghraoui.faure.recherche.entpe(AT)obelix.entpe.fr) [Apparently this email address is defunct]
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu)
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