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A103078
Numbers n such that 8*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 2, 4, 9, 10, 15, 44, 55, 56, 124, 140, 279, 674, 848, 1420, 1462, 3314, 3442, 4141, 35625
OFFSET
1,2
COMMENTS
Also numbers n such that (25*10^n+17)/3 is prime.
a(21) > 10^5. - Robert Price, Oct 20 2015
FORMULA
a(n) = A101065(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(25*10^n + 17)/3], Print[n]], {n, 0, 10000}]
PROG
(PARI) for(n=1, 1e3, if(isprime((25*10^n+17)/3), print1(n", "))) \\ Altug Alkan, Oct 20 2015
CROSSREFS
Sequence in context: A287413 A026602 A287436 * A060756 A075347 A352506
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(20) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
STATUS
approved