A217386 Emirps (A006567) whose difference with the reversal is a perfect square.

37, 73, 1237, 3019, 7321, 9103, 104801, 105601, 106501, 108401, 111211, 112111, 120121, 121021, 137831, 138731, 144541, 145441, 150151, 151051, 161561, 165161, 167861, 168761, 171271, 172171, 180181, 181081, 185681, 186581, 189337, 194891, 198491, 302647, 305603, 306503

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

Subsequence of A006567 and of A158065.

Sequence in context: A083748 A146273 A146241 * A083990 A123815 A289732

Adjacent sequences: A217383 A217384 A217385 * A217387 A217388 A217389

Keyword

nonn,base

Author

Antonio Roldán, Oct 02 2012

Status

approved