

A102999


Numbers n such that 4*10^n + 8*R_n  1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



0, 1, 2, 7, 14, 25, 116, 427, 595, 637, 776, 1706, 16628, 55558
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OFFSET

1,3


COMMENTS

Also numbers n such that (44*10^n17)/9 is prime.
a(15) > 10^5.  Robert Price, Jun 05 2015


LINKS

Table of n, a(n) for n=1..14.
Makoto Kamada, Prime numbers of the form 488...887.
Index entries for primes involving repunits.


FORMULA

a(n) = A101736(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(44*10^n  17)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101736.
Sequence in context: A249547 A088207 A194111 * A225277 A014112 A227016
Adjacent sequences: A102996 A102997 A102998 * A103000 A103001 A103002


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 17 2005


EXTENSIONS

Addition of a(13) from Kamada data by Robert Price, Dec 13 2010
a(14) from Robert Price, Jun 05 2015
Prepended a(1) = 0 by Robert Price, Jun 05 2015


STATUS

approved



