A074346 a(1) = 10; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.

10, 13, 23, 49, 111, 113, 171, 211, 293, 309, 333, 387, 463, 479, 513, 687, 933, 973, 993, 1329, 1433, 1449, 1551, 2071, 2271, 2423, 2587, 2621, 2659, 2757, 2771, 2911, 3081, 3243, 3279, 3671, 4243, 4247, 4371, 4453, 4511, 5229, 6097, 6177, 6293, 6571

Offset: 1

Author

Zak Seidov, Sep 23 2002

Keywords

• nonn
• base

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..439

Crossrefs

Cf. A111524, A111525, A074336.

Cf. A074338, A074339, A074340, A074341, A074342, A074343, A074344, A074345.

Programs

Mathematica

a[1] = 10; a[n_] := a[n] = Block[{k = a[n - 1] + 1 + Mod[a[n - 1], 2], c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 46}] (* Robert G. Wilson v, Aug 05 2005 *)

Python

from sympy import isprime
def aupton(terms):
    alst, astr = [10], "10"
    while len(alst) < terms:
        k = alst[-1] + 1 + (alst[-1]%2)
        while not isprime(int(astr+str(k))): k += 2
        alst.append(k)
        astr += str(k)
    return alst
print(aupton(46)) # Michael S. Branicky, Oct 13 2021

Extensions

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