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A093939 Primes of the form 3*10^n + 7*R_n, where R_n is the repunit (A002275) of length n. 1
3, 37, 377777777777, 377777777777777777 (list; graph; refs; listen; history; text; internal format)
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 n).

Sequence in context: A176245 A122787 A241895 * A129122 A002405 A050394

Adjacent sequences:  A093936 A093937 A093938 * A093940 A093941 A093942

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Apr 17 2004

STATUS

approved

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Last modified May 19 16:42 EDT 2019. Contains 323395 sequences. (Running on oeis4.)