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A128942 Numbers n such that the next prime exceeding 10^n is a twin prime member. 0
1, 2, 4, 9, 537, 1322, 1476 (list; graph; refs; listen; history; text; internal format)
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 * 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

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Last modified September 20 07:32 EDT 2021. Contains 347577 sequences. (Running on oeis4.)