A074599 Numerator of 2 * H(n,2,1), a generalized harmonic number. See A075135. Also 2 * A350669.

2, 8, 46, 352, 1126, 13016, 176138, 182144, 3186538, 62075752, 63461422, 1488711776, 7577414602, 23104065256, 680057071574, 21372905414144, 21646396991594, 21904260478904, 819482859775298, 828045249930848

Offset: 1

Author

Robert G. Wilson v, Aug 27 2002

Keywords

• nonn
• easy
• frac

Comments

2*(1 + 1/3 + ... + 1/(2*n-1))/Pi = a(n)/(A350670(n)*Pi) is the equivalent resistance between the points (0,0) and (n,n) on a 2-dimension infinite square grid of unit resistors. - Jianing Song, Apr 28 2025

Links

• MathPages, The Algebra of an Infinite Grid of Resistors
• Physics Stack Exchange, On this infinite grid of resistors, what's the equivalent resistance?

Crossrefs

Cf. A350669. The denominators are in A350670.

Cf. A025547, A025550, A075135.

Not always equal to the second left hand column of A161198 triangle divided by A025549. - Johannes W. Meijer, Jun 08 2009

Programs

Mathematica

Table[ Numerator[ Sum[1/i, {i, 1/2, n}]], {n, 1, 20}]