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 A072872 a(n) is the smallest positive number k such that n divides 2^k - k. 5
 1, 2, 4, 4, 3, 4, 11, 8, 5, 14, 7, 4, 10, 16, 16, 16, 30, 16, 30, 16, 11, 58, 75, 16, 34, 10, 5, 16, 6, 16, 8, 32, 58, 30, 16, 16, 58, 30, 10, 16, 33, 16, 54, 92, 16, 118, 224, 16, 36, 34, 59, 16, 36, 34, 63, 16, 130, 6, 64, 16, 43, 8, 16, 64, 16, 58, 210, 84, 118, 16, 43, 16, 32 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS If n is a power of 2, a(n) = n. Conjecture : if n > 47, a(n) < prime(n). LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 MATHEMATICA dvkn[n_]:=Module[{k=1}, While[!Divisible[2^k-k, n], k++]; k]; Array[dvkn, 80] (* Harvey P. Dale, Dec 23 2011 *) PROG (PARI) a(n) = for(k=1, oo, if(Mod(2, n)^k==k, return(k))); \\ Jinyuan Wang, Mar 15 2020 CROSSREFS See A135359 for another version. Cf. A247248. Sequence in context: A193358 A214028 A079533 * A135359 A098217 A151846 Adjacent sequences: A072869 A072870 A072871 * A072873 A072874 A072875 KEYWORD nonn,easy AUTHOR Benoit Cloitre, Jul 28 2002 EXTENSIONS Edited by N. J. A. Sloane, May 27 2010 STATUS approved

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Last modified February 25 05:55 EST 2024. Contains 370310 sequences. (Running on oeis4.)