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

Author

Alessandro Polcini, Feb 20 2017

Keywords

• nonn
• easy

Comments

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

Crossrefs

Cf. A001747, A139270, A176100.

Programs

PARI

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

Formula

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

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