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A093632
Primes of the form 7*10^k + R_k, where R_k is the repunit (A002275) of length k.
1
7, 71, 71111111, 71111111111111111111111111111111111111111111111111111111
OFFSET
1,1
COMMENTS
No further terms up to 2000 digits. - Harvey P. Dale, Mar 06 2012
MATHEMATICA
Select[Table[FromDigits[PadRight[{7}, n, 1]], {n, 2000}], PrimeQ] (* Harvey P. Dale, Mar 06 2012 *)
CROSSREFS
Cf. A002275, A056719 (corresponding k).
Sequence in context: A218384 A022503 A063861 * A242827 A077332 A222833
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Apr 06 2004
STATUS
approved