

A236670


Start with 6; thereafter, primes obtained by concatenating to the end of previous term the next smallest number that will produce a prime.


0



6, 61, 613, 6131, 613141, 61314119, 6131411917, 61314119171, 6131411917181, 613141191718127, 61314119171812789, 613141191718127893, 61314119171812789379, 6131411917181278937929, 61314119171812789379291, 61314119171812789379291111
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OFFSET

1,1


COMMENTS

a(n+1) is the next smallest prime beginning with a(n). Initial term is 6. After a(1), these are the primes arising in A069608.


LINKS



EXAMPLE

a(1) = 6 by definition.
a(2) is the next smallest prime beginning with 6, so a(2) = 61.
a(3) is the next smallest prime beginning with 61, so a(3) = 613.


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(6)


CROSSREFS



KEYWORD

nonn,base


AUTHOR



STATUS

approved



