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A088640 Smallest number suffixed to concatenation of n times n gives a prime. 1
2, 1, 3, 1, 9, 7, 29, 1, 3, 7, 39, 1, 23, 1, 97, 1, 91, 37, 59, 9, 93, 19, 97, 61, 293, 61, 3, 1, 57, 7, 43, 61, 7, 53, 31, 127, 353, 67, 841, 187, 9, 3, 179, 429, 127, 97, 3, 319, 11, 51, 39, 191, 33, 3, 41, 7, 39, 47, 73, 81, 401, 57, 441, 571, 957, 997, 1, 19, 291, 173, 9, 417 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..71.

EXAMPLE

a(6) = 29 and 66666629 is prime.

MAPLE

a:= proc(n) local d, h, s;

      s:= parse(cat(0, n$n));

      for d from 0 do

        for h to 10^d-1 do

          if isprime(s+h) then return h fi

        od:

        s:= s*10;

      od

    end:

seq(a(n), n=0..75);  # Alois P. Heinz, Feb 11 2021

CROSSREFS

Cf. A088639.

Sequence in context: A198315 A126761 A090559 * A186725 A301935 A237978

Adjacent sequences:  A088637 A088638 A088639 * A088641 A088642 A088643

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Oct 27 2003

EXTENSIONS

More terms from Ray Chandler, Nov 01 2003

a(0)=2 prepended by Alois P. Heinz, Feb 11 2021

STATUS

approved

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Last modified February 27 17:31 EST 2021. Contains 341657 sequences. (Running on oeis4.)