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A122862 Numbers k such that (9*10^k-11)/7 is prime. 1
2, 260, 650, 1928, 5768 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are of the form 2+6*k, k=0,1,... Next term > 7220. Are there any n's such that (9*10^n-11)/p is prime for prime p<>7? Cf. A100275 = Numbers n such that 9*10^n-11 is prime.

LINKS

Table of n, a(n) for n=1..5.

MATHEMATICA

Do[If[PrimeQ[(9*10^n-11)/7], Print[n]], {n, 2, 7220, 6}]

PROG

(PARI) is(n)=ispseudoprime((9*10^n-11)/7) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A100275.

Sequence in context: A089663 A252708 A103029 * A236437 A137105 A216984

Adjacent sequences:  A122859 A122860 A122861 * A122863 A122864 A122865

KEYWORD

nonn

AUTHOR

Zak Seidov, Sep 22 2006

STATUS

approved

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Last modified March 22 01:06 EDT 2019. Contains 321406 sequences. (Running on oeis4.)