OFFSET
1,1
LINKS
Andreas Boe, Table of n, a(n) for n = 1..10766
EXAMPLE
1961=37*53 has 4 digits and is the product of two 2-digit primes, and 1961 -> 19 and 61 also gives two 2-digit primes.
PROG
(PARI) isok(n) = (bigomega(n) == 2) && (len = #Str(n)) && !(len % 2) && (f=factor(n)) && prod(i=1, #f~, #Str(f[i, 1])== len/2) && isprime(n\10^(len/2)) && isprime(q=n % 10^(len/2)) && (#Str(q)== len/2); \\ Michel Marcus, Jun 10 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Andreas Boe, Jun 09 2014
STATUS
approved