A178466 Primes prime(k) such that the concatenation prime(k+1)//prime(k) is also prime.

3, 47, 53, 61, 131, 173, 199, 211, 233, 257, 353, 523, 587, 607, 619, 647, 653, 751, 797, 971, 991, 997, 1103, 1123, 1231, 1381, 1553, 1777, 1913, 1973, 1987, 2297, 2333, 2341, 2399, 2677, 2861, 3049, 3191, 3259, 3607, 3637, 3761, 3989

Offset: 1

Author

Carmine Suriano, Jan 27 2011

Keywords

• nonn
• base

Comments

53, 211, 653, 997, ... are also in A088712.

The role of the two primes is swapped in comparison to A030459.

The result of the concatenation is in A088784.

Examples

			The prime 53 is in the sequence because the next prime is 59 and 5953 is a prime.
		

Crossrefs

Cf. A030459, A030460, A088712.

Programs

Maple

read("transforms") ;
for n from 1 to 600 do p := ithprime(n) ; q := nextprime(p) ; r := digcat2(q,p) ; if isprime(r) then printf("%d,",p) ; end if; end do: # R. J. Mathar, Jan 27 2011

Mathematica

Transpose[Select[Partition[Prime[Range[600]],2,1],PrimeQ[FromDigits[ Flatten[ IntegerDigits/@Reverse[#]]]]&]][[1]]  (* Harvey P. Dale, Feb 02 2011 *)

Formula

a(n) = A151799(A088712(n)).