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URL: https://oeis.org/A217386

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A217386
Emirps (A006567) whose difference with the reversal is a perfect square.
4
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
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
KEYWORD
nonn,base
AUTHOR
Antonio Roldán, Oct 02 2012
STATUS
approved