A039696 If n = Product (p_j^k_j) then a(n) = Product (p_j) + Product (k_j).

2, 3, 4, 4, 6, 7, 8, 5, 5, 11, 12, 8, 14, 15, 16, 6, 18, 8, 20, 12, 22, 23, 24, 9, 7, 27, 6, 16, 30, 31, 32, 7, 34, 35, 36, 10, 38, 39, 40, 13, 42, 43, 44, 24, 17, 47, 48, 10, 9, 12, 52, 28, 54, 9, 56, 17, 58, 59, 60, 32, 62, 63, 23, 8, 66, 67, 68, 36, 70, 71, 72, 12, 74, 75

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• easy

Examples

			14 = 2^1*7^1, a(14) = 2*7 + 1*1 = 15.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005361, A007947.

Programs

Mathematica

Array[Times @@ #1 + Times @@ #2 & @@ Transpose@ FactorInteger[#] &, 74] (* Michael De Vlieger, Feb 18 2022 *)

PARI

a(n) = my(f=factor(n)); prod(k=1, #f~, f[k,1]) +  prod(k=1, #f~, f[k,2]); \\ Michel Marcus, Feb 18 2022

Formula

a(n) = A007947(n) + A005361(n).