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A093403 Primes of the form 50*R_n + 9, where R_n is the repunit (A002275) of length n. 2
59, 55555559, 555555555559, 555555555555555559, 55555555555555555555555559, 55555555555555555555555555555559, 555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555559 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form (5*10^n + 31)/9. - Vincenzo Librandi, Nov 17 2010

LINKS

Table of n, a(n) for n=1..7.

Makoto Kamada, Prime numbers of the form 55...559.

Index entries for primes involving repunits

FORMULA

a(n) = (50*10^A056687(n) + 31)/9 = (5*10^A099418(n) + 31)/9.

CROSSREFS

Cf. A056687 (corresponding n), A099418.

Sequence in context: A178066 A191947 A188269 * A087535 A058931 A092914

Adjacent sequences:  A093400 A093401 A093402 * A093404 A093405 A093406

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Mar 28 2004

EXTENSIONS

Edited by Ray Chandler, Feb 27 2012

STATUS

approved

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Last modified February 21 23:41 EST 2020. Contains 332113 sequences. (Running on oeis4.)