A105437 Smallest prime that remains prime when a string of n 1's is prepended to it.

2, 3, 3, 7, 3, 83, 31, 7, 3, 29, 3, 53, 23, 439, 23, 53, 31, 71, 31, 79, 89, 233, 7, 3, 227, 487, 281, 31, 7, 227, 47, 439, 29, 47, 349, 491, 43, 31, 23, 7, 919, 701, 229, 283, 281, 59, 223, 2693, 53, 67, 239, 2011, 2113, 467, 41, 601, 587, 311, 337, 2879, 59, 619, 71

Offset

0,1

Links

Table of n, a(n) for n=0..62.

Example

a(3)=7 because it is the first prime before 31,59,61,71,73,97,... all remaining prime when 111 is prepended to each of them.

Mathematica

f[n_] := Block[{k = 1, t = Table[1, {n}]}, While[id = IntegerDigits[ Prime[k]]; id[[1]] == 1 || !PrimeQ[ FromDigits[ Join[t, id]]], k++ ]; Prime[k]]; Table[ f[n], {n, 0, 62}] (* Robert G. Wilson v, Apr 09 2005 *)

Crossrefs

Cf. A105436, A065584.

Sequence in context: A023646 A056225 A343390 * A323952 A168140 A333699

Adjacent sequences: A105434 A105435 A105436 * A105438 A105439 A105440

Keyword

nonn,base

Author

Lekraj Beedassy, Apr 08 2005

Extensions

More terms from Robert G. Wilson v, Apr 09 2005

Status

approved