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A183176 Numbers n such that (10^(2n+1)+12*10^n-1)/3 is prime. 1
1, 3, 7, 11, 13, 17, 29, 31, 33, 77, 933, 1555, 11758 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(14) > 100,000. - Robert Price, Dec 29 2016

REFERENCES

C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

LINKS

Table of n, a(n) for n=1..13.

Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's)

Makoto Kamada, Prime numbers of the form 33...33733...33

Index entries for primes involving repunits.

FORMULA

a(n) = (A077790(n)-1)/2.

MATHEMATICA

Do[If[PrimeQ[(10^(2n + 1) + 12*10^n - 1)/3], Print[n]], {n, 3000}]

PROG

(PARI) is(n)=ispseudoprime((10^(2*n+1)+12*10^n-1)/3) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.

Sequence in context: A020618 A184865 A055211 * A045417 A260379 A045418

Adjacent sequences:  A183173 A183174 A183175 * A183177 A183178 A183179

KEYWORD

nonn,more,base

AUTHOR

Ray Chandler, Dec 28 2010

STATUS

approved

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Last modified September 20 16:22 EDT 2017. Contains 292276 sequences.