A103093 - OEIS

A103093

Numbers n such that 9*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

3, 4, 24, 39, 63, 76, 108, 166, 520, 1810, 2349, 2562, 5784, 6448, 11692, 16036, 17554

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OFFSET

1,1

COMMENTS

Also numbers n such that (83*10^n-11)/9 is prime.

a(18) > 10^5. - Robert Price, Nov 03 2015

LINKS

FORMULA

a(n) = A101001(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(83*10^n - 11)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

KEYWORD

more,nonn

AUTHOR

EXTENSIONS

a(15)-a(17) from Kamada data by Robert Price, Dec 14 2010

STATUS

approved