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A102973
Numbers n such that 3*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
0, 2, 3, 5, 8, 14, 77, 195, 218, 957, 1052, 1163, 1485, 1731, 1970, 3237, 17354, 85964
OFFSET
1,2
COMMENTS
Also numbers n such that (32*10^n+31)/9 is prime.
a(19) > 10^5. - Robert Price, May 31 2015
FORMULA
a(n) = A101838(n-1) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(32*10^n+31)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A196118 A104880 A152478 * A371992 A066372 A058519
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Addition of a(17) from Kamada data by Robert Price, Dec 12 2010
a(18) from Robert Price, May 31 2015
STATUS
approved