A102932 - OEIS

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A102932

Numbers k such that 10^k + 3*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

3

0, 1, 2, 4, 5, 12, 60, 109, 181, 245, 412, 887, 2477, 2918, 4622, 6240, 6253, 7684, 14630, 20932, 49801, 254107, 275671, 380056

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Also numbers k such that (4*10^k + 11)/3 is prime.

a(22) > 2*10^5. - Robert Price, Feb 17 2018

LINKS

Table of n, a(n) for n=1..24.

Makoto Kamada, Prime numbers of the form 133...337.

Index entries for primes involving repunits.

FORMULA

a(n) = A102013(n-1) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(4*10^n + 11)/3], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A102013.

Sequence in context: A353850 A050599 A281643 * A128457 A139485 A079407

Adjacent sequences: A102929 A102930 A102931 * A102933 A102934 A102935

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 16 2004

EXTENSIONS

Addition of a(19)-a(20) from Kamada data by Robert Price, Dec 10 2010

0 added by Arkadiusz Wesolowski, Mar 10 2011

a(21) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(22)-a(24) from Tyler Busby, Apr 20 2024

STATUS

approved