A113893 - OEIS

%I #8 Sep 27 2023 12:05:00

%S 23,37,523,719,1117,1319,1723,1931,2341,2953,3137,3761,4153,4373,4759,

%T 53101,59107,6173,6779,71167,73127,79103,8389,89101,97103,101107,

%U 103307,107137,109139,113131,127139,131149,137191,139199,149173,151157,157163

%N Smallest prime obtained as a concatenation of prime(n) and prime(m) with m > n.

%H Harvey P. Dale, <a href="/A113893/b113893.txt">Table of n, a(n) for n = 1..1000</a>

%e a(6) = 1319 as 1317 is composite. prime(6) = 13.

%t spc[n_]:=Module[{p1=Prime[n],p2},p2=NextPrime[p1];While[!PrimeQ[ p1* 10^IntegerLength[ p2]+p2],p2 = NextPrime[p2]];p1*10^IntegerLength[ p2]+p2]; Array[spc,40] (* _Harvey P. Dale_, Apr 05 2018 *)

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Nov 18 2005

%E More terms from _Stefan Steinerberger_ and _Jim Nastos_, Nov 18 2005