OFFSET
1,2
COMMENTS
Exactly every other term is prime; moreover the ending digit of a(n) and the initial digit of a(n+1) are never both prime or both composite.
LINKS
E. Angelini, Non-primes/primes: integers and digits alternate, SeqFan mailing list, Oct 06 2012
PROG
(PARI) A217559(n, show_all=0, a=1, u)={for( i=2, n, u+=1<<a; show_all & print1(a", "); for(t=1, 9e9, bittest(u, t) & next; isprime(t)==bittest(i, 0) & next; isprime(a%10) == isprime(t\10^(#Str(t)-1)) & (t+=10^(#Str(t)-1)-1) & next; a=t; break )); a}
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and M. F. Hasler, Oct 06 2012
STATUS
approved