A093939 Primes of the form 3*10^k + 7*R_k, where R_k is the repunit (A002275) of length k.

3, 37, 377777777777, 377777777777777777

Offset

1,1

Comments

a(5) has 774 digits, a(6) has 18156. - Vincenzo Librandi, Dec 10 2010

Links

Table of n, a(n) for n=1..4.

Makoto Kamada, Prime numbers of the form 377...77.

Index entries for primes involving repunits.

Crossrefs

Cf. A002275, A056705 (corresponding k).

Sequence in context: A176245 A122787 A241895 * A129122 A345688 A002405

Adjacent sequences: A093936 A093937 A093938 * A093940 A093941 A093942

Keyword

nonn

Author

Rick L. Shepherd, Apr 17 2004

Status

approved