This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A074599 #16 Apr 28 2025 12:22:08
%S A074599 2,8,46,352,1126,13016,176138,182144,3186538,62075752,63461422,
%T A074599 1488711776,7577414602,23104065256,680057071574,21372905414144,
%U A074599 21646396991594,21904260478904,819482859775298,828045249930848
%N A074599 Numerator of 2 * H(n,2,1), a generalized harmonic number. See A075135. Also 2 * A350669.
%C A074599 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
%H A074599 MathPages, <a href="https://www.mathpages.com/home/kmath669/kmath669.htm">The Algebra of an Infinite Grid of Resistors</a>
%H A074599 Physics Stack Exchange, <a href="https://physics.stackexchange.com/q/2072">On this infinite grid of resistors, what's the equivalent resistance?</a>
%t A074599 Table[ Numerator[ Sum[1/i, {i, 1/2, n}]], {n, 1, 20}]
%Y A074599 Cf. A350669. The denominators are in A350670.
%Y A074599 Cf. A025547, A025550, A075135.
%Y A074599 Not always equal to the second left hand column of A161198 triangle divided by A025549. - _Johannes W. Meijer_, Jun 08 2009
%K A074599 nonn,easy,frac
%O A074599 1,1
%A A074599 _Robert G. Wilson v_, Aug 27 2002