OFFSET
1,1
COMMENTS
The differences are multiples of 36.
LINKS
Antonio Roldán, Table of n, a(n) for a(n)<10^6
EXAMPLE
37 and 73 are primes. 73 - 37 = 36, which is 6^2.
302647 is prime, the reversal 746203 is also prime. 746203 - 302547 = 443556 = 666^2.
PROG
(PARI) isinteger(n)=(n==truncate(n))
reverse(n)=eval(concat(Vecrev(Str(n))))
isquare(n)= { local(f, m, p=0); if(n==1, p=1, f=factor(n); m=gcd(f[, 2]); if(isinteger(m/2), p=1)); return(p) }
{for(i=2, 10^7, p=reverse(i); if(isprime(i)&&isprime(p)&&isquare(abs(i-p)), print1(i, " ")))} /* Antonio Roldán, Dec 20 2012 */
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Antonio Roldán, Oct 02 2012
STATUS
approved