A130122 - OEIS

%I #6 Apr 17 2017 14:37:43

%S 3,5,7,11,13,17,41,67,89,101,109,181,193,199,223,227,283,313,337,347,

%T 367,419,421,449,461,479,491,587,641,647,709,727,773,811,823,827,857,

%U 859,863,881,887,911,953,1021,1049,1063,1091,1181,1217,1361,1399,1447

%N Primes prime(n) such that 10*prime(n)+prime(n+2) is prime.

%H Harvey P. Dale, <a href="/A130122/b130122.txt">Table of n, a(n) for n = 1..1000</a>

%e a(7)=41 because 10*41+47=457 and 457 is prime,

%e a(8)=67 because 10*67+73=743 and 743 is prime,

%e a(9)=89 because 10*89+101=991 and 991 is prime, ...

%p ts_p6_01:=proc(n) local a,b,i,ans; ans := [ ]: for i from 1 to n do a := 10*ithprime(i)+ithprime(i+2): if (isprime(a)=true) then ans := [ op(ans), ithprime(i) ]: fi od; RETURN(ans) end: ts_p6_01(1000);

%t Select[Partition[Prime[Range[300]],3,1],PrimeQ[10#[[1]]+#[[3]]]&][[All,1]] (* _Harvey P. Dale_, Apr 17 2017 *)

%Y Cf. A129900.

%K nonn

%O 1,1

%A _Jani Melik_, Aug 01 2007