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A368823
a(1) = 1; for n > 1, a(n) = A055231(a(n-1) * n), where A055231(k) is the powerfree part of k.
2
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.
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
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Jan 07 2024
STATUS
approved