OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
Concatenation of prime 2 and second prime 3 is the prime 23, hence 2 is in the sequence.
Concatenation of prime 23 and 23rd prime 83 is the prime 2383, hence 23 is in the sequence.
MATHEMATICA
A154963 = Select[ Prime[ Range[ 550 ] ], PrimeQ[ FromDigits[ Join[ IntegerDigits[ # ], IntegerDigits[ Prime[ # ] ] ] ] ] & ] (* Alonso del Arte Nov 12 2009 *)
PROG
(Magma) [ p: p in PrimesUpTo(3700) | IsPrime(StringToInteger(IntegerToString(p) cat IntegerToString(NthPrime(p)))) ];
KEYWORD
nonn,base,easy,less
AUTHOR
Juri-Stepan Gerasimov, Jan 18 2009
EXTENSIONS
Edited and extended beyond a(3) by Klaus Brockhaus, Jan 20 2009
STATUS
approved