A069613 a(1) = 1; a(2n) = smallest prime starting ( the most significant digits) with a(2n-1). and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

1, 11, 211, 2111, 22111, 2211127, 12211127, 122111279, 14122111279, 1412211127927, 211412211127927, 21141221112792721, 1321141221112792721, 132114122111279272169, 27132114122111279272169, 2713211412211127927216947

Offset

1,2

Links

Table of n, a(n) for n=1..16.

Example

a(4) = 2111 starting with a(3) =211 and a(5) = 22111 ending in a(4) = 2111.

Crossrefs

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611.

Sequence in context: A176009 A068836 A069628 * A075858 A136307 A249604

Adjacent sequences: A069610 A069611 A069612 * A069614 A069615 A069616

Keyword

nonn,base

Author

Amarnath Murthy, Mar 27 2002

Extensions

More terms from Robert Gerbicz, Aug 27 2002

Status

approved