A100759 Beginning with 2, least prime not occurring earlier such that the concatenation of first n terms has the least prime factor prime(n).

2, 7, 5, 17, 127, 3, 347, 37, 71, 829, 89, 79, 311, 271, 1103, 823, 827, 7219, 149, 499, 3947, 6367, 2861, 3673, 13781, 2281, 281, 229, 353, 1597, 191, 1879, 2609, 10993, 19961, 4789, 383, 1093, 521, 13681, 9227, 12619, 8219, 12037, 8573, 7621, 6029

Offset: 1

Author

Amarnath Murthy, Nov 23 2004

Keywords

• base
• less
• nonn

Comments

Conjecture: Every prime is a member.

Examples

			a(1) = 2, a(2) = 7 and the least prime divisor of 27 is 3.
		

Crossrefs

Cf. A114025.

Programs

Mathematica

a = {2}; b = 2; Do[i = 1; While[Length[Intersection[a, {Prime[i]}]] == 1, i++ ]; While[ !FactorInteger[FromDigits[Join[IntegerDigits[b], IntegerDigits[Prime[i]]]]][[1, 1]] == Prime[n], i++ ]; AppendTo[a, Prime[i]]; b = FromDigits[Join[IntegerDigits[b], IntegerDigits[Prime[i]]]], {n, 2, 30}]; a (* Stefan Steinerberger, Dec 21 2007 *)

Extensions

More terms from Stefan Steinerberger, Dec 21 2007

More terms from David Wasserman, Mar 04 2008