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 A097447 Primes in the concatenation of consecutive prime-sided isosceles triangles. 0

%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

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Last modified May 28 19:36 EDT 2023. Contains 363019 sequences. (Running on oeis4.)