A103024 - OEIS

A103024

Numbers n such that 5*10^n + 8*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 4, 8, 13, 16, 44, 439, 608, 1201, 2725, 5210, 59389, 118216, 198529

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OFFSET

1,2

COMMENTS

Also numbers n such that (53*10^n+1)/9 is prime.

LINKS

FORMULA

a(n) = A101589(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(53*10^n + 1)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

KEYWORD

more,nonn

AUTHOR

EXTENSIONS

Addition of a(12)-a(14) from Kamada data by Robert Price, Dec 12 2010

STATUS

approved