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Search: id:A043772
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| A043772 |
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Numbers n such that all divisors of n are lucky numbers. |
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+0
2
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| 1, 3, 7, 9, 13, 21, 31, 37, 43, 49, 63, 67, 73, 79, 93, 111, 127, 129, 151, 163, 169, 193, 201, 211, 219, 223, 237, 241, 259, 283, 307, 331, 349, 367, 409, 421, 433, 463, 487, 489, 511, 541, 553, 559, 577, 579, 601, 613, 619, 631, 643, 673, 723, 727, 739, 769
(list; graph; listen)
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OFFSET
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1,2
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MATHEMATICA
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lst = Range[1, 776, 2]; i = 2; While[ i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; fQ[n_] := Block[{d = Rest@Divisors@n, k = 1, lmt = DivisorSigma[0, n]}, While[k < lmt && MemberQ[lst, d[[k]]], k++ ]; k == lmt]; Select[lst, fQ@# &] (from Robert G. Wilson v (rgwv(at)rgwv.com), May 12 2006)
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CROSSREFS
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Cf. A000959.
Sequence in context: A103601 A111250 A118643 this_sequence A109370 A018663 A110575
Adjacent sequences: A043769 A043770 A043771 this_sequence A043773 A043774 A043775
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KEYWORD
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easy,nonn
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AUTHOR
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Naohiro Nomoto (6284968128(AT)geocities.co.jp), Oct 08 2000
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