A183177 Numbers n such that (10^(2n+1)+15*10^n-1)/3 is prime.

1, 7, 85, 94, 273, 356, 1077, 1797, 6758, 30232

Offset

1,2

Comments

a(11) > 10^5. - Robert Price, Apr 21 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..10.

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

Makoto Kamada, Prime numbers of the form 33...33833...33

Index entries for primes involving repunits.

Formula

a(n) = (A077792(n)-1)/2.

Mathematica

Do[If[PrimeQ[(10^(2n + 1) + 15*10^n - 1)/3], Print[n]], {n, 3000}]

Prog

(PARI) is(n)=ispseudoprime((10^(2*n+1)+15*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: A258174 A370934 A254569 * A367351 A058795 A027459

Adjacent sequences: A183174 A183175 A183176 * A183178 A183179 A183180

Keyword

nonn,more,base

Author

Ray Chandler, Dec 28 2010

Extensions

a(10) from Robert Price, Apr 21 2016

Status

approved