A387140 a(n) = (1/n) * Product_{k=1..n} radical(k) for n >= 1, a(0) = 1, where radical(n) is the product of distinct prime factors of n, cf. A007947.

1, 1, 1, 2, 3, 12, 60, 360, 630, 1680, 15120, 151200, 831600, 9979200, 129729600, 1816214400, 3405402000, 54486432000, 308756448000, 5557616064000, 52797352608000, 1055947052160000, 22174888095360000, 487847538097920000, 2805123344063040000, 13464592051502592000

Offset: 0

Author

Peter Luschny, Aug 18 2025

Keywords

• nonn
• new

Crossrefs

Cf. A007947, A048803, A387141.

Programs

Maple

a := n -> if n = 0 then 1 else mul(NumberTheory:-Radical(i), i=1..n) / n fi:

Mathematica

A387140[n_] := If[n == 0, 1, Quotient[Times @@ ResourceFunction["IntegerRadical"][Range[1, n]], n]]; Table[A387140[n], {n, 0, 25}]

Formula

a(n) = A048803(n) / n for n >= 1.