A189100 a(n) = lcm(n!,n!')/gcd(n!,n!'), where n!' is the arithmetic derivative of n! (A068311).

0, 2, 30, 66, 1830, 645, 33180, 198870, 228270, 64785, 7960260, 9738960, 1663226565, 7232635410, 857066210, 1057466410, 307311194190, 767464487790, 278292627277665, 306517823106495, 35302033071305, 147385363695570, 78207294248313230, 198777858520921680

Offset

1,2

Comments

Least common multiple of n! and its arithmetic derivative divided by greatest common divisor of n! and its arithmetic derivative.

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..200

Formula

a(n) = lcm(n!,n!')/gcd(n!,n!') = A086130(n!)/A085731(n!) = lcm(A000142(n),A068311(n))/gcd(A000142(n),A068311(n))

Example

n = 5: 5! = 120, 120' = 244, gcd(120,244) = 4, lcm(120,244) = 7320, 7320/4 = 1830 -> a(5) = 1830.

Crossrefs

A068311, A083346, A083346, A085731, A086130

Sequence in context: A105403 A134644 A244379 * A085637 A193177 A379319

Adjacent sequences: A189097 A189098 A189099 * A189101 A189102 A189103

Keyword

nonn

Author

Giorgio Balzarotti, Apr 16 2011

Status

approved