cp's OEIS Frontend

A260907 Numbers n such that prime(n) + prime(n+1) + prime(n+2) is not a prime.

%I A260907 #23 Sep 08 2022 08:46:13
%S A260907 1,2,6,12,14,15,17,21,24,25,27,28,30,31,32,33,36,39,40,41,42,43,44,46,
%T A260907 48,49,51,52,53,54,55,56,57,59,63,65,66,67,71,72,73,74,76,78,81,82,84,
%U A260907 85,86,89,92,93,96,98,99,100,102,103,104,105,106,107,108
%N A260907 Numbers n such that prime(n) + prime(n+1) + prime(n+2) is not a prime.
%C A260907 Complement of A072225.
%e A260907 6 is in the sequence because prime(6) + prime(7) + prime(8) = 13 + 17 + 19 = 49 is not a prime.
%t A260907 Select[Range[200], !PrimeQ[Prime[#] + Prime[# + 1] + Prime[# + 2]] &]
%o A260907 (Magma) [n: n in [1..200] | not IsPrime(NthPrime(n) + NthPrime(n+1) + NthPrime(n+2))];
%o A260907 (PARI) for(n=1, 1e2, if(!isprime(prime(n)+prime(n+1)+prime(n+2)), print1(n, ", "))) \\ _Altug Alkan_, Nov 19 2015
%o A260907 (Sage) [n for n in (1..200) if not is_prime(nth_prime(n) + nth_prime(n+1) + nth_prime(n+2))] # _Bruno Berselli_, Nov 19 2015
%Y A260907 Cf. A000040, A072225, A174742 (associated primes).
%K A260907 nonn,easy
%O A260907 1,2
%A A260907 _Vincenzo Librandi_, Nov 18 2015