|
%I #6 Oct 01 2013 17:58:02
%S 233,577,192323,798383,109113113,113127127,127131131,149151151,
%T 181191191,197199199,223227227,239241241,241251251,337347347,
%U 431433433,461463463,479487487,491499499,641643643,643647647,683691691,709719719
%N Primes in the concatenation of consecutive prime-sided isosceles triangles.
%C Is this sequence infinite?
%F Consider triangles with sides (2, 3, 3), (3, 5, 5), .., (x, y, y) where x is prime and y is the next prime after x. Concatenate these sides and output if prime.
%e For side x = 19, y = 23 and 192323 is prime.
%o (PARI) f(n) = for(x=1,n,y=Str(prime(x));y=concat(y,concat(Str(prime(x+1)),Str(prime (x+1))));if(isprime(eval(y)),print1(y",")))
%K nonn,base
%O 1,1
%A _Cino Hilliard_, Aug 23 2004
%E Edited by _Charles R Greathouse IV_, Apr 29 2010
|
