login
A103017
Numbers n such that 5*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
0, 1, 2, 4, 7, 22, 28, 36, 109, 155, 868, 1777, 2465, 3874, 4506, 4684, 5503, 13975, 15632, 33054, 34307, 50495, 60631, 62328, 92513, 92869
OFFSET
1,3
COMMENTS
Also numbers n such that (17*10^n-11)/3 is prime.
a(27) > 10^5. - Robert Price, Jul 29 2015
FORMULA
a(n) = A101582(n-1) + 1 for n>1.
MATHEMATICA
Do[ If[ PrimeQ[(17*10^n - 11)/3], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A337062 A153550 A102984 * A091833 A171978 A290571
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(18)-a(19) from Kamada data by Robert Price, Dec 14 2010
a(20)-a(21) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
Prepended a(1)=0 by Robert Price, Jul 29 2015
a(22)-a(26) from Robert Price, Jul 29 2015
STATUS
approved