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 A140667 Odd composite numbers k for which k = A140607((k-1)/2). 3
 91, 1581, 2465, 8481, 25761, 31609, 33355, 34945, 118405, 146611, 319507, 736291, 994507, 3270403, 3375487, 5176153, 6186403, 6228685, 8650951, 10679131, 22028203, 26017291, 31470211, 33796531, 41710411, 42149971, 42474547, 46672291, 48316969, 49019851, 58986091, 68182003, 69885649 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..33. PROG (PARI) f(n) = (eulerphi(2*n+1) + 1 + g(n))/2; \\ A140607 g(n) = sumdiv(2*n+1, d, eulerphi(d)/(t=znorder(Mod(2, d))))*t-t+1; \\ A137576 isok(c) = if (!isprime(c) && (c%2), f((c-1)/2) == c); \\ Michel Marcus, Jan 31 2023 CROSSREFS Cf. A140607, A039649, A140140, A138193, A138217, A138227, A138535, A138536, A138537, A138539, A140141, A000010, A000040, A140608, A138786. Sequence in context: A120756 A027787 A333112 * A221939 A254611 A184462 Adjacent sequences: A140664 A140665 A140666 * A140668 A140669 A140670 KEYWORD nonn AUTHOR Ray Chandler, May 20 2008 EXTENSIONS More terms from Michel Marcus, Jan 31 2023 STATUS approved

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Last modified June 2 22:56 EDT 2023. Contains 363102 sequences. (Running on oeis4.)