A064167 Product of numerator and denominator of the n-th harmonic number, 1 + 1/2 + 1/3 +...+ 1/n.

1, 6, 66, 300, 8220, 980, 50820, 213080, 17965080, 18600120, 2320468920, 2384502120, 412970037480, 422245703880, 430902992520, 1756076802480, 516336630329520, 58297387228080, 21362271268818480, 866533600973040, 97555876321904, 98772315738096, 52866073370045936, 481103506052529360

Offset: 1

Author

Leroy Quet, Sep 19 2001

Keywords

• nonn

Comments

Numerator and denominator in definition have no common divisors >1.

Examples

			The 3rd harmonic number is 11/6. So a(3) = 11 * 6 = 66.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001008, A002805, A064168, A064169.

Programs

Mathematica

Numerator[#]Denominator[#]&/@HarmonicNumber[Range[30]] (* Harvey P. Dale, May 01 2022 *)

PARI

a(n) = my(h=sum(k=1, n, 1/k)); numerator(h) * denominator(h); \\ Michel Marcus, Sep 07 2019

Extensions

More terms from Michel Marcus, Sep 07 2019