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A102934
Numbers k such that 10^k + 4*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
1
1, 3, 4, 6, 9, 22, 28, 34, 37, 61, 82, 274, 276, 735, 1443, 2215, 2968, 3301, 3883, 3991, 5152, 8032, 8946, 46642, 57691
OFFSET
1,2
COMMENTS
Also numbers k such that (13*10^k + 23)/9 is prime.
a(26) > 10^5. - Robert Price, Feb 19 2015
a(26) > 2*10^5. - Tyler Busby, Feb 01 2023
FORMULA
a(n) = A102016(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(13*10^n + 23)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A301657 A241342 A018830 * A338061 A350741 A191699
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 16 2004
EXTENSIONS
a(24) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
a(25) from Robert Price, Feb 19 2015
STATUS
approved