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 A192868 Thin numbers: odd numbers k > 1 such that k+1 is a prime times a power of two. 3
 3, 5, 7, 9, 11, 13, 15, 19, 21, 23, 25, 27, 31, 33, 37, 39, 43, 45, 47, 51, 55, 57, 61, 63, 67, 73, 75, 79, 81, 85, 87, 91, 93, 95, 103, 105, 111, 115, 117, 121, 123, 127, 133, 135, 141, 145, 147, 151, 157, 159, 163, 165, 171, 175, 177, 183, 187, 191, 193 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 Kevin A. Broughan and Zhou Qizhi, Flat primes and thin primes, Bulletin of the Australian Mathematical Society, Vol. 82, No. 2 (2010), pp. 282-292, alternative link. FORMULA a(n) ~ n log n. MATHEMATICA Select[Range[3, 200, 2], (r = (# + 1)/2^IntegerExponent[# + 1, 2]) == 1 || PrimeQ[r] &] (* Amiram Eldar, Aug 30 2020 *) PROG (PARI) is(n)=n%2&&(isprime((n+1)>>valuation(n+1, 2)) || n+1 == 1<1 CROSSREFS Cf. A192869. Sequence in context: A204458 A192861 A333854 * A283553 A081110 A143449 Adjacent sequences:  A192865 A192866 A192867 * A192869 A192870 A192871 KEYWORD nonn AUTHOR Charles R Greathouse IV, Jul 11 2011 STATUS approved

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Last modified May 16 22:18 EDT 2021. Contains 343957 sequences. (Running on oeis4.)