A370354 Composite numbers k that share a factor with sopfr(k), the sum of the primes dividing k, with repetition.

4, 8, 9, 16, 18, 24, 25, 27, 30, 32, 36, 42, 49, 50, 60, 64, 66, 70, 72, 78, 81, 84, 98, 100, 102, 105, 110, 114, 120, 121, 125, 126, 128, 130, 132, 138, 140, 144, 150, 154, 156, 160, 162, 168, 169, 170, 174, 180, 182, 186, 190, 192, 195, 196, 200, 204, 216, 220, 222, 228, 230, 231, 234, 238, 240

Offset: 1

Author

Scott R. Shannon, May 06 2024

Keywords

• nonn

Comments

All prime powers, see A246547, are terms.

Examples

			18 is a term as 18 = 2 * 3 * 3, and soprf(18) = 2 + 3 + 3 = 8, which shares a factor with 18.
		

Links

• Scott R. Shannon, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001414, A002808, A027746, A246547, A046346, A372524.

Programs

Mathematica

fn[{a_,b_}]:=a*b;Select[Range[240],CompositeQ[#]&&ContainsAny[First/@FactorInteger[#],First/@FactorInteger[ Total[fn/@FactorInteger[#]]]]&] (* James C. McMahon, May 06 2024 *)