A033679 a(1) = 2; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.

2, 3, 3, 3, 3, 21, 53, 69, 81, 139, 143, 223, 233, 261, 261, 399, 553, 609, 659, 673, 1017, 1187, 1357, 1571, 1641, 1839, 2151, 2191, 2499, 2511, 2607, 2667, 2681, 3081, 3351, 4291, 4319, 4353, 4489, 4733, 4819, 6003, 6011, 6631, 6797, 7113, 7429, 7547, 7651

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..300

Maple

R:= 2, 3: p:= 23: x:= 3:
for count from 3 to 100 do
  for y from x by 2 do
    if isprime(10^(1+ilog10(y))*p+y) then
      R:= R, y; p:= 10^(1+ilog10(y))*p+y; x:= y;
      break
    fi
od od:
R; # Robert Israel, Nov 22 2020

Mathematica

a[1] = 2; a[n_] := a[n] = Block[{k = a[n - 1], c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k ++ ]; k]; Table[ a[n], {n, 47}] (* Robert G. Wilson v, Aug 05 2005 *)

Crossrefs

Cf. A069603, A074338, A033680, A033681, A046254, A046255, A046256, A046257, A046258, A046259, A111524.

Sequence in context: A210794 A268607 A069603 * A051670 A089702 A089336

Adjacent sequences: A033676 A033677 A033678 * A033680 A033681 A033682

Keyword

nonn,base

Author

N. J. A. Sloane

Extensions

More terms from Patrick De Geest, May 15 1998

More terms from Robert G. Wilson v, Aug 05 2005

Status

approved