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A106092 Even numbers and primes. 2
2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 22, 23, 24, 26, 28, 29, 30, 31, 32, 34, 36, 37, 38, 40, 41, 42, 43, 44, 46, 47, 48, 50, 52, 53, 54, 56, 58, 59, 60, 61, 62, 64, 66, 67, 68, 70, 71, 72, 73, 74, 76, 78, 79, 80, 82, 83, 84, 86, 88, 89, 90, 92, 94, 96, 97 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Paulo A. Martin, The Galois group of x^n-x^(n-1)-...-x-1, Journal of Pure and Applied Algebra, Volume 190, Issues 1-3, 1 June 2004, Pages 213-223.

FORMULA

From Robert Israel, Jan 01 2019: (Start)

a(k-1+A000720(2*k)] = 2*k.

a((prime(k)-3)/2 + k] = prime(k) for k >= 2. (End)

MAPLE

map(op, [seq([2*k, `if`(isprime(2*k+1), 2*k+1, NULL)], k=1..100)]); # Robert Israel, Jan 01 2019

MATHEMATICA

Union[Prime[Range[30]], Select[Range[113], EvenQ]]

DeleteCases[Range[2, 100], _?(OddQ[#]&&CompositeQ[#]&)] (* Harvey P. Dale, Dec 04 2021 *)

PROG

(PARI) isok(n) = isprime(n) || ((n%2) == 0); \\ Michel Marcus, Feb 24 2020

CROSSREFS

Cf. A000720.

Complement of A014076.

Sequence in context: A307646 A246786 A095949 * A210940 A257500 A121208

Adjacent sequences: A106089 A106090 A106091 * A106093 A106094 A106095

KEYWORD

nonn

AUTHOR

Zak Seidov, May 07 2005

STATUS

approved

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Last modified December 4 04:59 EST 2022. Contains 358544 sequences. (Running on oeis4.)