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 A038699 Smallest prime of form n*2^m-1, m >= 0, or 0 if no such prime exists. 16
 3, 3, 2, 3, 19, 5, 13, 7, 17, 19, 43, 11, 103, 13, 29, 31, 67, 17, 37, 19, 41, 43, 367, 23, 199, 103, 53, 223, 463, 29, 61, 31, 131, 67, 139, 71, 73, 37, 311, 79, 163, 41, 5503, 43, 89, 367, 751, 47, 97, 199, 101, 103, 211, 53, 109, 223, 113, 463, 241663, 59, 487, 61 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..650 MATHEMATICA getm[n_]:=Module[{m=0}, While[!PrimeQ[n 2^m-1], m++]; n 2^m-1]; Array[getm, 80]  (* Harvey P. Dale, Apr 24 2011 *) PROG (Haskell) a038699 = until ((== 1) . a010051) ((+ 1) . (* 2)) . (subtract 1) -- Reinhard Zumkeller, Mar 05 2012 CROSSREFS Primes arising in A040081 (or 0 if no prime exists). Cf. A040081, A050921. Cf. A010051, A000079. Sequence in context: A123676 A122775 A086632 * A249803 A064655 A207335 Adjacent sequences:  A038696 A038697 A038698 * A038700 A038701 A038702 KEYWORD nonn,easy,nice AUTHOR N. J. A. Sloane, Dec 30 1999 EXTENSIONS More terms from Henry Bottomley, Apr 24 2001 STATUS approved

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Last modified August 17 21:06 EDT 2018. Contains 313817 sequences. (Running on oeis4.)