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 A339880 Odd composite numbers k such that A053575(k) [the odd part of phi] divides k-1. 9
 15, 51, 85, 91, 255, 435, 451, 561, 595, 771, 1105, 1261, 1285, 1351, 1695, 2091, 2431, 2465, 3655, 3855, 4369, 4795, 5083, 5151, 5383, 6601, 6643, 6735, 7051, 8245, 8481, 8695, 8911, 8995, 9061, 9605, 10585, 11155, 13107, 15051, 15211, 16405, 16705, 17733, 18721, 19669, 20451, 21845, 22359, 23001, 26335, 28645 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS No common terms with A016105. See A339870 for the reason. - Antti Karttunen, Dec 26 2020 LINKS Antti Karttunen, Table of n, a(n) for n = 1..1237 PROG (PARI) A000265(n) = (n>>valuation(n, 2)); isA339880(n) = (bitand(n, 1)&&(n>1)&&!isprime(n)&&!((n-1)%A000265(eulerphi(n)))); CROSSREFS Cf. A000010, A000265, A016105, A053575. Subsequence of A005117 and of A339879, and of A340077. Cf. A339869, A339870 (subsequences). Cf. also A002997, A053576, A339817. Sequence in context: A333314 A238575 A020144 * A235040 A075933 A075929 Adjacent sequences:  A339877 A339878 A339879 * A339881 A339882 A339883 KEYWORD nonn AUTHOR Antti Karttunen, Dec 24 2020 STATUS approved

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Last modified April 16 05:26 EDT 2021. Contains 343030 sequences. (Running on oeis4.)