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A260907 Numbers n such that prime(n) + prime(n+1) + prime(n+2) is not a prime. 0
1, 2, 6, 12, 14, 15, 17, 21, 24, 25, 27, 28, 30, 31, 32, 33, 36, 39, 40, 41, 42, 43, 44, 46, 48, 49, 51, 52, 53, 54, 55, 56, 57, 59, 63, 65, 66, 67, 71, 72, 73, 74, 76, 78, 81, 82, 84, 85, 86, 89, 92, 93, 96, 98, 99, 100, 102, 103, 104, 105, 106, 107, 108 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Complement of A072225.

LINKS

Table of n, a(n) for n=1..63.

EXAMPLE

6 is in the sequence because prime(6) + prime(7) + prime(8) = 13 + 17 + 19 = 49 is not a prime.

MATHEMATICA

Select[Range[200], !PrimeQ[Prime[#] + Prime[# + 1] + Prime[# + 2]] &]

PROG

(MAGMA) [n: n in [1..200] | not IsPrime(NthPrime(n) + NthPrime(n+1) + NthPrime(n+2))];

(PARI) for(n=1, 1e2, if(!isprime(prime(n)+prime(n+1)+prime(n+2)), print1(n, ", "))) \\ Altug Alkan, Nov 19 2015

(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

CROSSREFS

Cf. A000040, A072225, A174742 (associated primes).

Sequence in context: A250178 A154712 A079849 * A333833 A057895 A111369

Adjacent sequences:  A260904 A260905 A260906 * A260908 A260909 A260910

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 18 2015

STATUS

approved

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Last modified September 17 01:53 EDT 2021. Contains 347478 sequences. (Running on oeis4.)