A377401 a(n) = denominator((1/n!)*Sum_{k=1..n} 1/(2*k)).

1, 2, 8, 72, 576, 14400, 28800, 470400, 22579200, 1828915200, 18289152000, 2212987392000, 26555848704000, 4487938430976000, 62831138033664000, 942467070504960000, 30158946256158720000, 8715935468029870080000, 52295612808179220480000, 18878716223752698593280000

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Formula

Conjecture: numerator((1/n!)*Sum_{k=1..n} 1/(2*k)) = A060746(n).

Mathematica

a[n_]:=Denominator[Sum[1/(2*k), {k, n}]/n!]; Array[a, 20, 0]

Prog

(PARI) a(n) = denominator(sum(k=1, n, 1/(2*k))/n!); \\ Michel Marcus, Oct 29 2024

Crossrefs

Cf. A000142, A005843, A060746, A377400.

Sequence in context: A296629 A026739 A060635 * A364408 A194499 A009478

Adjacent sequences: A377398 A377399 A377400 * A377402 A377403 A377404

Keyword

nonn,frac

Author

Stefano Spezia, Oct 27 2024

Status

approved