cp's OEIS Frontend

A117675 Numbers k such that prime(k) + prime(k+1) + prime(k+2) is prime and also there is a j such that prime(j) + prime(j+1) + prime(j+2) = prime(k).

%I A117675 #15 Jul 23 2024 03:10:57
%S A117675 9,11,13,20,23,29,47,64,70,88,121,126,145,148,153,174,190,195,201,213,
%T A117675 223,245,294,298,320,337,369,381,429,436,445,462,486,495,504,536,548,
%U A117675 584,596,608,639,677,747,819,827,831,868,877,887,902,905,970
%N A117675 Numbers k such that prime(k) + prime(k+1) + prime(k+2) is prime and also there is a j such that prime(j) + prime(j+1) + prime(j+2) = prime(k).
%o A117675 (PARI)
%o A117675 isok2(k)={my(q=prime(k), p=q\3); while(p>2, p=precprime(p-1); my(p2=nextprime(p+1), t=p+p2+nextprime(p2+1)); if(t<=q, return(t==q))); 0}
%o A117675 isok(k)={my(p1=prime(k), p2=nextprime(p1+1), p3=nextprime(p2+1)); isprime(p1+p2+p3) && isok2(k)}
%o A117675 select(isok, [1..1000]) \\ _Andrew Howroyd_, Jul 23 2024
%Y A117675 Cf. A109756, A072225.
%K A117675 nonn
%O A117675 1,1
%A A117675 _Roger L. Bagula_, Apr 12 2006
%E A117675 Edited and more terms from _Andrew Howroyd_, Jul 23 2024