A128942 Numbers n such that the next prime exceeding 10^n is a twin prime member.

1, 2, 4, 9, 537, 1322, 1476

Offset

1,2

Comments

A003617(a(n)) is in A001097 (Twin primes).

Links

Table of n, a(n) for n=1..7.

Example

For n=2, 10^2 = 100. The first prime > 100 is 101 which is a member of the twin prime pair 101,103.

Mathematica

tpQ[n_]:=Module[{pr=NextPrime[10^n]}, Or@@PrimeQ[{pr-2, pr+2}]]; Select[ Range[ 1500], tpQ] (* Harvey P. Dale, Aug 05 2012 *)

Prog

(PARI) g(n)=for(x=1, n, y=nextprime(10^x); if(ispseudoprime(y+2), print1(x", ")))

Crossrefs

Sequence in context: A269739 A065299 A292114 * A364637 A328837 A302349

Adjacent sequences: A128939 A128940 A128941 * A128943 A128944 A128945

Keyword

hard,more,nonn

Author

Cino Hilliard, Apr 28 2007

Extensions

Edited by Ray Chandler, May 12 2007

a(6), a(7) from Donovan Johnson, Feb 21 2008

Status

approved