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A093403
Primes of the form 50*R_k + 9, where R_k is the repunit (A002275) of length k.
2
59, 55555559, 555555555559, 555555555555555559, 55555555555555555555555559, 55555555555555555555555555555559
OFFSET
1,1
COMMENTS
Primes of the form (5*10^k + 31)/9. - Vincenzo Librandi, Nov 17 2010
FORMULA
a(n) = (50*10^A056687(n) + 31)/9 = (5*10^A099418(n) + 31)/9.
CROSSREFS
Cf. A056687 (corresponding k), A099418.
Sequence in context: A235215 A178066 A191947 * A087535 A058931 A092914
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Mar 28 2004
EXTENSIONS
Edited by Ray Chandler, Feb 27 2012
STATUS
approved