A069613 a(1) = 1; a(2n) is smallest prime starting with a(2n-1) and a number with no insignificant zeros, and a(2n+1) is smallest prime ending in 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

Author

Amarnath Murthy, Mar 27 2002

Keywords

• nonn
• base

Comments

a(6) is not 2211109 because the 0 in this number is considered insignificant (for comparison, the 0 in 22111109 would be significant, but this value is not the smallest possible extension of a(5)=22111). - Sean A. Irvine, May 07 2024

Examples

			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, A069614.

Extensions

More terms from Robert Gerbicz, Aug 27 2002

Name clarified by Sean A. Irvine, May 07 2024