A208572 Smallest twin prime > 2^n.

3, 5, 11, 17, 41, 71, 137, 269, 521, 1031, 2081, 4127, 8219, 16451, 32801, 65537, 131111, 262151, 524351, 1048889, 2097257, 4194581, 8388617, 16777289, 33554501, 67109321, 134217779, 268435577, 536871017, 1073741831, 2147483867, 4294967387

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..500

Example

For n=1 the smallest twin prime > 2^n is 3.

Mathematica

stp[n_]:=Module[{t=NextPrime[n]}, While[!PrimeQ[t+2], t=NextPrime[t]]; t]; Table[stp[2^i], {i, 40}] (* Harvey P. Dale, Aug 24 2013 *)

Prog

(PARI) a(n)=my(t=2^n); while(!ispseudoprime(t+2), t=nextprime(t+1)); t \\ Charles R Greathouse IV, Jun 21 2012

Crossrefs

Cf. A001359, A208574, A173937 (a(n) - 2^n).

Sequence in context: A128550 A096479 A129809 * A040176 A092873 A158641

Adjacent sequences: A208569 A208570 A208571 * A208573 A208574 A208575

Keyword

nonn

Author

Washington Bomfim, Feb 28 2012

Status

approved