A111667 Abundance of admirable numbers.

4, 2, 12, 12, 10, 12, 12, 8, 12, 4, 12, 56, 4, 12, 2, 12, 120, 12, 56, 12, 12, 12, 56, 78, 12, 12, 180, 12, 56, 12, 12, 56, 12, 8, 12, 12, 12, 2, 12, 56, 12, 56, 12, 12, 12, 12, 12, 56, 2, 12, 672, 12, 12, 12, 56, 12, 12, 8, 56, 12, 12, 12, 30, 12, 32, 12, 56, 12, 12, 12, 12, 56

Offset: 1

Author

Jason Earls, Aug 14 2005

Keywords

• easy
• nonn

Examples

			a(1)=4 because the first admirable number is 12 and sigma(12)-24 = 4.
		

Links

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

Crossrefs

Cf. A033880, A111592.

Programs

Mathematica

fn[n_]:=DivisorSigma[1,n]-2*n;fn/@Select[Range[1155], MemberQ[Most[Divisors[#]], (DivisorSigma[1, #]-2*#)/2]&] (* James C. McMahon, Jun 02 2024 *)