A079111 Numbers n such that 2*n+1 or n itself is prime.

1, 2, 3, 5, 6, 7, 8, 9, 11, 13, 14, 15, 17, 18, 19, 20, 21, 23, 26, 29, 30, 31, 33, 35, 36, 37, 39, 41, 43, 44, 47, 48, 50, 51, 53, 54, 56, 59, 61, 63, 65, 67, 68, 69, 71, 73, 74, 75, 78, 79, 81, 83, 86, 89, 90, 95, 96, 97, 98, 99, 101, 103, 105, 107, 109, 111, 113, 114, 116

Offset

1,2

Comments

Union of A000040 and A005097; complement of A077654.

Links

Table of n, a(n) for n=1..69.

Formula

a(n) ~ (n log n)/2. - Charles R Greathouse IV, Jun 13 2017

Prog

(PARI) is(n)=isprime(n) || isprime(2*n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A341763 A201144 A095274 * A346725 A346726 A346724

Adjacent sequences: A079108 A079109 A079110 * A079112 A079113 A079114

Keyword

nonn

Author

Reinhard Zumkeller, Dec 24 2002

Status

approved