A030456 a(0) = 2; a(n) is smallest prime containing a(n-1) as substring.

2, 23, 223, 1223, 12239, 122393, 1223939, 12239393, 122393939, 1223939399, 12239393993, 122393939933, 12239393993311, 412239393993311, 8412239393993311, 78412239393993311, 2378412239393993311, 23784122393939933111, 2623784122393939933111, 26237841223939399331111

Offset: 0

Author

Patrick De Geest

Keywords

• nonn
• base

Links

• Sean A. Irvine, Table of n, a(n) for n = 0..100 (first 17 terms from Zak Seidov)
• Sean A. Irvine, Java program (github)

Crossrefs

Cf. A068167.

Programs

Mathematica

FromDigits /@ Nest[Append[#, Block[{p = NextPrime@ FromDigits@ #[[-1]], d}, While[Length@ SequencePosition[Set[d, IntegerDigits@ p], #[[-1]]] == 0, p = NextPrime@ p]; d]] &, {{2}}, 7] (* Michael De Vlieger, Feb 26 2018 *)

Extensions

a(17) onward from Zak Seidov, Nov 02 2009

a(19) corrected by Andrew Howroyd, Feb 26 2018

a(17) onward corrected by Sean A. Irvine, Apr 01 2020