A244271 - OEIS

%I #10 Jun 20 2021 17:31:31

%S 17,53,181,313,829,859,1151,1493,2011,2161,2267,2287,2371,2521,2549,

%T 2791,2803,3019,3617,3821,4273,4481,4483,4493,5081,5351,5399,5669,

%U 5851,6067,6197,6529,6781,6833,8123,8329,8527,8597,9277,10631,10771,11119,11801,11807,11941,12149,12239,12421,12479,12743,13033

%N Primes p such that p1p2p3p4p5p6p7p8p9p is prime.

%H Harvey P. Dale, <a href="/A244271/b244271.txt">Table of n, a(n) for n = 1..1000</a>

%e 53 is prime and 53153253353453553653753853953 is prime. Thus 53 is a member of this sequence.

%t Select[Prime[Range[1600]],PrimeQ[FromDigits[Flatten[ IntegerDigits/@ Riffle[ PadRight[ {},10,#],Range[ 9]]]]]&] (* _Harvey P. Dale_, Jun 20 2021 *)

%o (PARI) for(n=1,10^4,b="";for(i=2,20,if(i==Mod(1,2),b=concat(b,Str((i-1)/2)));if(i==Mod(0,2),b=concat(b,Str(prime(n)))));if(ispseudoprime(eval(b)),print1(prime(n),", ")))

%Y Cf. A244270.

%K nonn,base,less

%O 1,1

%A _Derek Orr_, Jun 24 2014