A368810 a(n) = numerator of Sum_{i=1..n} Sum_{j=1..n} (1/i + 1/j).

2, 6, 11, 50, 137, 147, 363, 1522, 7129, 7381, 83711, 86021, 1145993, 1171733, 1195757, 4873118, 42142223, 42822903, 275295799, 279175675, 56574159, 19093197, 444316699, 1347822955, 34052522467, 34395742267, 312536252003, 315404588903, 9227046511387

Offset: 1

Author

Mats Granvik, Jan 06 2024

Keywords

• nonn
• frac

Crossrefs

Cf. A027611, A096620 (denominators), A193758.

Programs

Mathematica

Numerator[Table[Sum[Sum[1/i + 1/j, {i, 1, n}], {j, 1, n}], {n, 1, 29}]]

Python

from sympy import harmonic
def A368810(n): return ((n<<1)*harmonic(n)).p # Chai Wah Wu, Feb 04 2024