A215641 Smallest prime whose decimal expansion consists of the concatenation of a 1-digit prime, a 2-digit prime, a 3-digit prime, ..., and an n-digit prime.

2, 211, 211151, 2111011129, 211101100910009, 211101100910007100049, 2111011009100071000031000453, 211101100910007100003100000310000721, 211101100910007100003100000310000019100000543, 2111011009100071000031000003100000191000000071000000531

Offset: 1

Author

Jonathan Vos Post, Aug 18 2012

Keywords

• nonn
• base

Comments

It is a plausible conjecture that a(n) always exists.

a(n) has A000217(n) = n*(n+1)/2 digits.

Examples

			a(4) = 2111011129, the smallest prime formed from a single-digit, a double-digit, a triple-digit, and a quadruple-digit prime, i.e., 2, 11, 101, 1129.
		

Crossrefs

Cf. A000040, A000217, A003617.

Subsequence of A195302.

Cf. A338968 (similar, with largest prime).

Extensions

Edited by N. J. A. Sloane, Aug 18 2012