A152678 Even members of A000203.

4, 6, 12, 8, 18, 12, 28, 14, 24, 24, 18, 20, 42, 32, 36, 24, 60, 42, 40, 56, 30, 72, 32, 48, 54, 48, 38, 60, 56, 90, 42, 96, 44, 84, 78, 72, 48, 124, 72, 98, 54, 120, 72, 120, 80, 90, 60, 168, 62, 96, 104, 84, 144, 68, 126, 96, 144

Offset: 1

Author

Omar E. Pol, Dec 10 2008

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A028983, A152677, A152679.

Programs

Mathematica

Select[DivisorSigma[1,Range[100]],EvenQ] (* Harvey P. Dale, Jun 18 2017 *)

PARI

list(lim) = select(x -> !(x % 2), vector(lim, i, sigma(i))); \\ Amiram Eldar, Dec 26 2024

Formula

a(n) = sigma(A028983(n)) = A000203(A028983(n)). - Jaroslav Krizek, Oct 06 2009