A104206 Concatenation of the smallest and the largest n-digit primes.

27, 1197, 101997, 10099973, 1000799991, 100003999983, 10000039999991, 1000001999999989, 100000007999999937, 10000000079999999967, 1000000001999999999977, 100000000003999999999989, 10000000000399999999999971, 1000000000003799999999999973

Offset

0,1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..499

Chris Caldwell The First 10,000 Primes

Example

27 is obtained by concatenating the smallest 1-digit prime and the largest 1-digit prime.
1197 is obtained by concatenating the smallest 2-digit prime and the largest 2-digit prime.

Maple

for n from 0 to 30 do for m from 1 to 10^(n+1)-1 do if isprime(10^n + m) then printf(`%d`, 10^n+m); break; fi: od: for m from 1 to 10^(n+1)-1 do if isprime(10^(n+1) - m) then printf(`%d`, 10^(n+1)-m); break; fi: od: printf(`, `): od: # James A. Sellers, May 02 2005

Mathematica

FromDigits/@Table[Flatten[{IntegerDigits[NextPrime[10^n]], IntegerDigits[ NextPrime[ 10^(n+1), -1]]}], {n, 0, 15}] (* Harvey P. Dale, Aug 06 2013 *)

Crossrefs

Sequence in context: A290946 A223552 A357228 * A327596 A163568 A066300

Adjacent sequences: A104203 A104204 A104205 * A104207 A104208 A104209

Keyword

nonn,base,less

Author

Parthasarathy Nambi, Apr 01 2005

Extensions

More terms from James A. Sellers, May 02 2005

Edited by Charles R Greathouse IV, Apr 27 2010

More terms from Harvey P. Dale, Aug 06 2013

Status

approved