OFFSET
1,1
MATHEMATICA
a = {51}; For[n = 3, n < 500, n++, If[Prime[n + 1] == Prime[n] + 2, AppendTo[a, FromDigits[Join[IntegerDigits[Prime[n + 1]], IntegerDigits[Prime[n]]]]]]]; Select[a/3, PrimeQ[ # ] &]
PROG
(PARI) concattwins3r(n) = { local(x, y); forprime(x=2, n, if(isprime(x+2), y=floor(eval(concat(Str(x+2), Str(x)))/3); print1(y", ") ) ) }
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Cino Hilliard, Jun 05 2007
EXTENSIONS
Edited and extended by Stefan Steinerberger, Aug 02 2007
STATUS
approved