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Search: id:A114562
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| 1, 4, 3, 8, 5, 36, 7, 16, 9, 20, 11, 72, 13, 28, 15, 32, 17, 108, 19, 40, 21, 44, 23, 144, 25, 52, 27, 56, 29, 900, 31, 64, 33, 68, 35, 216, 37, 76, 39, 80, 41, 252, 43, 88, 45, 92, 47, 288, 49, 100, 51, 104, 53, 324, 55, 112, 57, 116, 59, 1800, 61, 124, 63, 128, 65, 396, 67
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OFFSET
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1,2
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COMMENT
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A111701: Least integer obtained when n is divided by prime(1), then by prime(2), then by prime(3),..., stopping as soon as one of the primes does not divide it. In particular, a(2n-1) = 2n-1.
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FORMULA
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a(2n-1) = 2n-1, & a(2n) = k*4n for some k>0, if 2n == 0 (mod 3) then k = 3, if 2n ==0 (15 mod) k = 3*5, if 2n ==0 (105 mod) k = 3*5*7, if 2n ==0 (1155 mod) k = 3*5*7*11, etc.
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MATHEMATICA
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f[n_] := Block[{m = n, k = 1}, While[ IntegerQ[ m/Prime@k], m = m/Prime@k; k++ ]; m]; g[n_] := Block[{k = 1}, While[f@k != n, k++ ]; k]; Array[g, 67]
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CROSSREFS
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Cf. A111701, Complement of this sequence A095300.
Sequence in context: A086938 A126084 A007015 this_sequence A011451 A117956 A110662
Adjacent sequences: A114559 A114560 A114561 this_sequence A114563 A114564 A114565
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 04 2006
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