A084191 a(n) = A084190(A084190(n)).

1, 1, 1, 2, 3, 36, 10, 60, 21, 157080, 36, 2394591020640, 330, 438900, 702, 185640, 105, 392201962392240, 680, 47347883887966200, 450574740, 3183089069160, 210

Offset

1,4

Comments

Next term: a(24) = A084190(53130) > 10^91.

B-file goes up to n=59 because a(60) has 1503 digits. - Robert Israel, Sep 04 2019

Links

Robert Israel, Table of n, a(n) for n = 1..59

Maple

A084190:= n -> ilcm(op(map(`-`, numtheory:-divisors(n) minus {1}, 1))):
map(A084190@A084190, [$1..30]); # Robert Israel, Sep 04 2019

Mathematica

b[n_] := LCM @@ (Rest[Divisors[n]] - 1);
a[n_] := If[n <= 2, 1, b@b@n];
Array[a, 59] (* Jean-François Alcover, Dec 16 2021 *)

Crossrefs

Cf. A084190.

Sequence in context: A042663 A072291 A325500 * A080357 A064032 A118443

Adjacent sequences: A084188 A084189 A084190 * A084192 A084193 A084194

Keyword

nonn

Author

Reinhard Zumkeller, May 18 2003

Status

approved