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A093162 Primes of the form 20*R_n + 3, where R_n is the repunit (A002275) of length n. 3
3, 23, 223, 22222223, 22222222223, 222222222222222222222222222222222223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..6.

Makoto Kamada, Prime numbers of the form 22...223.

Index entries for primes involving repunits

FORMULA

a(n) = (20*10^A056656(n) + 7)/9 = (2*10^A096506(n) + 7)/9.

CROSSREFS

Cf. A002275, A056656 (corresponding n, and count of digits 2 in a(n)), A096506.

Sequence in context: A093135 A305754 A202997 * A206763 A306154 A201205

Adjacent sequences:  A093159 A093160 A093161 * A093163 A093164 A093165

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Mar 26 2004

EXTENSIONS

Edited by Ray Chandler, Feb 27 2012

STATUS

approved

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Last modified September 15 14:53 EDT 2019. Contains 327078 sequences. (Running on oeis4.)