A368823 a(1) = 1; for n > 1, a(n) = A055231(a(n-1) * n), where A055231(k) is the powerfree part of k.

1, 2, 6, 3, 15, 10, 70, 35, 35, 14, 154, 231, 3003, 858, 1430, 715, 12155, 24310, 461890, 46189, 969969, 176358, 4056234, 676039, 676039, 104006, 104006, 7429, 215441, 6463230, 200360130, 100180065, 367326905, 43214930, 60500902, 30250451, 1119266687, 117817546, 4594884294, 11487210735

Offset

1,2

Comments

Terms are squarefree. - Michael De Vlieger, Jan 07 2024.

Links

Table of n, a(n) for n=1..40.

Example

a(4) = 3 as a(3)*4 = 6*4 = 24 = 2*2*2*3, and the powerfree part of 24 is 3.

Mathematica

f[x_] := Times @@ Map[#1^(#2 Boole[#2 == 1]) & @@ # &, FactorInteger[x]]; a[n_] := f[n* a[n - 1]]; a[1] = 1; Array[a, 120] (* Michael De Vlieger, Jan 07 2024 *)

Crossrefs

Cf. A368825 (addition), A055231, A005117, A124010.

Sequence in context: A094299 A304537 A330252 * A372000 A121566 A056839

Adjacent sequences: A368820 A368821 A368822 * A368824 A368825 A368826

Keyword

nonn

Author

Scott R. Shannon, Jan 07 2024

Status

approved