A382213 Largest squarefree number dividing the numerator of harmonic number H(n).

1, 3, 11, 5, 137, 7, 33, 761, 7129, 671, 83711, 6617, 1145993, 1171733, 1195757, 143327, 42142223, 751279, 275295799, 55835135, 18858053, 830139, 444316699, 1347822955, 34052522467, 34395742267, 312536252003, 10876020307, 214582477009, 300151059037, 290774257297357

Offset: 1

Author

Ali Sada, Mar 22 2025

Keywords

• nonn

Examples

			A001008(4) = 25, and the largest squarefree divisor of 25 is 5, so a(4) = 5.
		

Crossrefs

Cf. A382329, A001008, A002805, A007913.

Cf. A333196.

Programs

Maple

a:= n-> mul(i[1], i=ifactors(numer(harmonic(n)))[2]):
seq(a(n), n=1..35);  # Alois P. Heinz, Apr 23 2025

PARI

a(n) = factorback(factor(numerator(sum(k=1, n, 1/k)))[, 1]); \\ Michel Marcus, Apr 24 2025

Formula

a(n) = A007947(A001008(n)).