OFFSET
1,2
COMMENTS
a(23) > 10^5. - Robert Price, Jan 29 2016
REFERENCES
C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
LINKS
Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's).
Makoto Kamada, Prime numbers of the form 33...33133...33.
FORMULA
a(n) = (A077775(n) - 1)/2.
MATHEMATICA
Do[If[PrimeQ[(10^(2n + 1) - 6*10^n - 1)/3], Print[n]], {n, 3000}]
PROG
(PARI) for(n=1, 1e3, if(ispseudoprime((10^(2*n+1)-6*10^n-1)/3), print1(n", "))) \\ Charles R Greathouse IV, Jul 15 2011
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Dec 28 2010
EXTENSIONS
a(21)-a(22) from Robert Price, Jan 29 2016
STATUS
approved