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 A289154 Smallest prime p > 2^n such that none of p -+ 2^0, p -+ 2^1, p -+ 2^2, ..., p -+ 2^n are prime. 1
 5, 23, 53, 211, 251, 787, 787, 1409, 1777, 1777, 1973, 3181, 4889, 8363, 19583, 34171, 66683, 131701, 263227, 527099, 1049011, 2098027, 4196407, 8389001, 16779001, 33555517, 67108913, 134219273, 268435537, 536871743, 1073743303, 2147485673, 4294968857 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 0..200 EXAMPLE a(0) = 5 because prime 5 > 2^0 = 1 and none of 5 - 2^0 = 4, 5 + 2^0 = 6 are prime, a(1) = 23 because prime 23 > 2^1 = 2 and none of 23 - 2^2 = 22, 23 + 2^0 = 24, 23 - 2^1 = 21, 23 + 2^1 = 25 are prime, a(2) = 53 because prime 53 > 2^2 = 4 and none of 53 - 2^0 = 52, 53 + 2^0 = 54, 53 - 2^1 = 51, 53 + 2^1 = 55, 53 - 2^2 = 49, 53 + 2^2 = 57 are prime. MATHEMATICA Table[p = NextPrime[2^n]; While[AnyTrue[p + Flatten@ Map[2^Range[0, n] # &, {-1, 1}], PrimeQ], p = NextPrime@ p]; p, {n, 0, 32}] (* Michael De Vlieger, Jun 27 2017 *) PROG (PARI) a(n)=if(n<1, return(5)); forprime(p=2^n+1, , for(k=1, n, if(isprime(p+2^k) || isprime(p-2^k), next(2))); return(p)) \\ Charles R Greathouse IV, Jul 07 2017 CROSSREFS Cf. A120937. Sequence in context: A338977 A090686 A082277 * A155851 A019267 A053664 Adjacent sequences:  A289151 A289152 A289153 * A289155 A289156 A289157 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Jun 26 2017 EXTENSIONS More terms from Michael De Vlieger, Jun 27 2017 a(15) corrected by Charles R Greathouse IV, Jul 07 2017 STATUS approved

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Last modified January 20 04:53 EST 2021. Contains 340301 sequences. (Running on oeis4.)