OFFSET
1,1
COMMENTS
All the terms in this sequence, except a(1), are congruent to 2 (mod 3).
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2) = 257 is prime formed by concatenation of (5^2) = 25 with 7.
a(3) = 12113 is prime formed by concatenation of (11^2) = 121 with 13.
MATHEMATICA
Select[Table[p = Prime[n]; FromDigits[Join[Flatten[ IntegerDigits[{p^2, NextPrime[p]}]]]], {n, 500}], PrimeQ]
Select[#[[1]]^2*10^IntegerLength[#[[2]]]+#[[2]]&/@Partition[Prime[ Range[ 300]], 2, 1], PrimeQ] (* Harvey P. Dale, Dec 05 2016 *)
PROG
(PARI) forprime(p = 1, 5000, k=eval(concat( Str(p^2), Str(nextprime(p+1)) )); if(isprime(k), print1(k, ", ")))
(Magma) [m: n in [1..300] | IsPrime(m) where m is Seqint(Intseq(NthPrime(n+1)) cat Intseq(NthPrime(n)^2))]; // Vincenzo Librandi, May 24 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, May 23 2015
STATUS
approved