A236671 Start with 8; thereafter, primes obtained by concatenating to the end of previous term the next smallest number that will produce a prime.

8, 83, 839, 83911, 839117, 83911721, 8391172123, 83911721233, 839117212337, 83911721233729, 839117212337293, 83911721233729399, 839117212337293999, 83911721233729399993, 839117212337293999931, 83911721233729399993139

Offset

1,1

Comments

a(n+1) is the next smallest prime beginning with a(n). Initial term is 8. After a(1), these are the primes arising in A069610.

Links

Table of n, a(n) for n=1..16.

Example

a(1) = 8 by definition.
a(2) is the next smallest prime beginning with 8, so a(2) = 83.
a(3) is the next smallest prime beginning with 83, so a(3) = 839.

Prog

(Python)
import sympy
from sympy import isprime
def b(x):
..num = str(x)
..n = 1
..while n < 10**3:
....new_num = str(x) + str(n)
....if isprime(int(new_num)):
......print(int(new_num))
......x = new_num
......n = 1
....else:
......n += 1
b(8)

Crossrefs

Cf. A069610, A048553, A110773,

Sequence in context: A196482 A196715 A179980 * A232226 A238811 A307829

Adjacent sequences: A236668 A236669 A236670 * A236672 A236673 A236674

Keyword

nonn,base

Author

Derek Orr, Jan 29 2014

Status

approved