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URL: https://oeis.org/A074346

⇱ A074346 - OEIS

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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.
12
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
1,1
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..439
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 *)
PROG
(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
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Sep 23 2002
EXTENSIONS
More terms from Robert G. Wilson v, Aug 05 2005
STATUS
approved