A282671 Twice composite numbers.

8, 12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 44, 48, 50, 52, 54, 56, 60, 64, 66, 68, 70, 72, 76, 78, 80, 84, 88, 90, 92, 96, 98, 100, 102, 104, 108, 110, 112, 114, 116, 120, 124, 126, 128, 130, 132, 136, 138, 140, 144, 148, 150, 152, 154, 156, 160, 162, 164, 168, 170, 172, 174

Offset

1,1

Comments

Even numbers greater than 2 that do not appear in A001747.

Links

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

Formula

a(n) = 2*A002808(n). - R. J. Mathar, Feb 23 2017

a(n) = A139270(n+1). - R. J. Mathar, Feb 25 2017

Prog

(PARI) is(n)=n%2==0 && n>6 && !isprime(n/2) \\ Charles R Greathouse IV, Feb 21 2017

Crossrefs

Cf. A001747, A139270, A176100.

Sequence in context: A166083 A326111 A091375 * A192991 A083348 A174261

Adjacent sequences: A282668 A282669 A282670 * A282672 A282673 A282674

Keyword

nonn,easy

Author

Alessandro Polcini, Feb 20 2017

Status

approved