OFFSET
1,1
EXAMPLE
10 is included since there are four primes between 10 and 1 and four primes between 10 and 20.
PROG
(PARI) ok(n)={my(r=fromdigits(Vecrev(digits(n)))); if(r>n, primepi(2*n) == primepi(r), primepi(n) - primepi(r-1) == primepi(2*n) - primepi(n-1))}
{ for(n=1, 10^5, if(ok(n), print1(n, ", "))) } \\ Andrew Howroyd, Feb 12 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Jason Earls, Sep 08 2002
EXTENSIONS
More terms from Sascha Kurz, Feb 10 2003
Terms a(28) and beyond from Andrew Howroyd, Feb 12 2020
STATUS
approved