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 A262385 #31 Aug 29 2018 02:51:17
%S A262385 1,60,336,21600,133056,825552000,89100,11435424000,483113030400,
%T A262385 101889627840000,1471926193920,42280119968486400,3425059028160,
%U A262385 209827678712652000,1184296360402995840,163066081742403840000,1749151741873536000,20373357051590182072392960000
%N A262385 Denominators of a semi-convergent series leading to the second Stieltjes constant gamma_2.
%C A262385 gamma_2 = - 1/60 + 5/336 - 469/21600 + 6515/133056 - 131672123/825552000 + ..., see formulas (46)-(47) in the reference below.
%H A262385 G. C. Greubel, <a href="/A262385/b262385.txt">Table of n, a(n) for n = 1..500</a>
%H A262385 Iaroslav V. Blagouchine, <a href="http://dx.doi.org/10.1016/j.jnt.2015.06.012">Expansions of generalized Euler's constants into the series of polynomials in 1/pi^2 and into the formal enveloping series with rational coefficients only.</a> Journal of Number Theory (Elsevier), vol. 158, pp. 365-396, 2016. <a href="http://arxiv.org/abs/1501.00740">arXiv version</a>, arXiv:1501.00740 [math.NT], 2015.
%F A262385 a(n) = denominator(B_{2n}*(H^2_{2n-1}-H^(2)_{2n-1})/(2n)), where B_n, H_n and H^(k)_n are Bernoulli, harmonic and generalized harmonic numbers respectively.
%F A262385 a(n) = denominator(-Zeta(1 - 2*n)*(Psi(1,2*n) + (Psi(0,2*n) + gamma)^2 - (Pi^2)/6)), where gamma is Euler's gamma and Psi is the digamma function. - _Peter Luschny_, Apr 19 2018
%e A262385 Denominators of 0/1, -1/60, 5/336, -469/21600, 6515/133056, -131672123/825552000, ...
%p A262385 a := n -> denom(-Zeta(1 - 2*n)*(Psi(1, 2*n) + (Psi(0,2*n) + gamma)^2 - (Pi^2)/6)):
%p A262385 seq(a(n), n=1..18); # _Peter Luschny_, Apr 19 2018
%t A262385 a[n_] := Denominator[BernoulliB[2*n]*(HarmonicNumber[2*n - 1]^2 - HarmonicNumber[2*n - 1, 2])/(2*n)]; Table[a[n], {n, 1, 20}]
%o A262385 (PARI) a(n) = denominator(bernfrac(2*n)*(sum(k=1,2*n-1,1/k)^2 - sum(k=1,2*n-1,1/k^2))/(2*n)); \\ _Michel Marcus_, Sep 23 2015
%Y A262385 Cf. A001620, A002206, A195189, A075266, A262235, A001067, A006953, A082633, A262382, A262383, A086279, A262384 (numerators of this series), A086280, A262386, A262387.
%K A262385 nonn,frac
%O A262385 1,2
%A A262385 _Iaroslav V. Blagouchine_, Sep 20 2015