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A183184
Numbers n such that 10^(2n+1)-8*10^n-1 is prime.
4
1, 5, 13, 43, 169, 181, 1579, 18077, 22652, 157363
OFFSET
1,2
REFERENCES
C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
FORMULA
a(n) = (A077776(n)-1)/2.
MATHEMATICA
Do[If[PrimeQ[10^(2n + 1) - 8*10^n - 1], Print[n]], {n, 3000}]
PROG
(PARI) is(n)=ispseudoprime(10^(2*n+1)-8*10^n-1) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Dec 28 2010
EXTENSIONS
Added one more term from PWP table, by Patrick De Geest, Nov 05 2014
STATUS
approved