OFFSET
1,1
COMMENTS
LINKS
Jean-Marc Falcoz, Table of n, a(n) for n = 1..7135
EXAMPLE
11 (prime) is the concatenation of "1" (nonprime) and "1" (nonprime); the next prime term cannot be 13 as "3" is a concatenated prime; the next prime term cannot be 17 as "7" is a concatenated prime; the next prime term is 19 as "1" and "9" are both nonprimes; the next prime term cannot be less than 41 because all terms < 41 and > 19 start with either a "2" or a "3", which are primes; etc.
PROG
(PARI) is(n)=if(!isprime(n), return(0)); my(d=digits(n)); for(i=2, #d, if(d[i] && !isprime(fromdigits(d[1..i-1])) && !isprime(fromdigits(d[i..#d])), return(1))); 0 \\ Charles R Greathouse IV, Nov 28 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Nov 28 2016
STATUS
approved