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 A060257 Numbers k such that 1/prime(k) has period prime(k) - 1. 4
 4, 7, 8, 9, 10, 15, 17, 18, 25, 29, 30, 32, 35, 39, 41, 42, 44, 48, 50, 51, 55, 56, 57, 65, 68, 73, 75, 76, 77, 81, 84, 89, 93, 94, 95, 96, 97, 100, 105, 106, 108, 114, 118, 120, 126, 127, 129, 132, 141, 142, 143, 148, 150, 154, 159, 160, 162, 164, 165, 166, 171 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 Matt Parker and Brady Haran, The Reciprocals of Primes, Numberphile video (2022) FORMULA a(n) = PrimePi(A001913(n)). - Alexander Adamchuk, Jan 28 2007 MATHEMATICA Select[Range[200], MultiplicativeOrder[10, (p = Prime[#])] == p - 1 &] (* Amiram Eldar, Oct 03 2021 *) CROSSREFS Cf. A060258. Cf. A000720 (PrimePi), A001913 (primes with primitive root 10). Sequence in context: A000934 A180692 A004710 * A262874 A309264 A161986 Adjacent sequences: A060254 A060255 A060256 * A060258 A060259 A060260 KEYWORD nonn AUTHOR Jeff Burch, Mar 22 2001 STATUS approved

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Last modified September 10 12:58 EDT 2024. Contains 375790 sequences. (Running on oeis4.)