A088244 Number of 3-smooth divisors of n!.

1, 1, 2, 4, 8, 8, 15, 15, 24, 40, 45, 45, 66, 66, 72, 84, 112, 112, 153, 153, 171, 190, 200, 200, 253, 253, 264, 336, 364, 364, 405, 405, 480, 512, 528, 528, 630, 630, 648, 684, 741, 741, 800, 800, 840, 924, 946, 946, 1081, 1081, 1104, 1152, 1200, 1200

Offset

0,3

Links

Amiram Eldar, Table of n, a(n) for n = 0..10000

Formula

a(n) = A072078(A000142(n)).

a(n) = a(n-1) iff gcd(n,6) = 1.

a(n) = (A011371(n)+1)*(A054861(n)+1).

Mathematica

a[n_] := ((1 + IntegerExponent[n!, 2])*(1 + IntegerExponent[n!, 3])); Array[a, 100, 0] (* Amiram Eldar, Aug 30 2019 *)

Crossrefs

Cf. A000005, A003586.

Cf. A000142, A072078.

Cf. A011371, A054861.

Sequence in context: A181533 A263981 A362936 * A073616 A076735 A192097

Adjacent sequences: A088241 A088242 A088243 * A088245 A088246 A088247

Keyword

nonn

Author

Reinhard Zumkeller, Jan 23 2004

Status

approved