A329930 a(n) = n!^2*(Sum_{k=1..n} 1/k).

0, 1, 6, 66, 1200, 32880, 1270080, 65862720, 4418426880, 372523898880, 38569208832000, 4811724352512000, 712008517828608000, 123312192439468032000, 24712050750746591232000, 5674212235766262988800000, 1479958528399750515916800000, 435149988031383614993203200000

Offset

0,3

Comments

For n>=1, a(n) is the number of vertices of the harmonic polytope. See Ardila and Escobar.

Links

Table of n, a(n) for n=0..17.

Federico Ardila and Laura Escobar, The harmonic polytope, arXiv:2006.03078 [math.CO], 2020.

Formula

a(n) = A000142(n)*A000254(n).

Prog

(PARI) a(n) = n!^2*sum(k=1, n, 1/k);

Crossrefs

Cf. A000142, A000254.

Sequence in context: A229002 A122020 A262601 * A367308 A271220 A259123

Adjacent sequences: A329927 A329928 A329929 * A329931 A329932 A329933

Keyword

nonn

Author

Michel Marcus, Jun 08 2020

Status

approved