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

1,1

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

Table of n, a(n) for n=1..20.

MathPages, The Algebra of an Infinite Grid of Resistors

Physics Stack Exchange, On this infinite grid of resistors, what's the equivalent resistance?

Mathematica

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

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

Sequence in context: A294784 A180390 A300696 * A007289 A099765 A385367

Adjacent sequences: A074596 A074597 A074598 * A074600 A074601 A074602

Keyword

nonn,easy,frac

Author

Robert G. Wilson v, Aug 27 2002

Status

approved