

A128942


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


0




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[{pr2, 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 * A328837 A302349 A135445
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



