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 A258991 #12 Feb 16 2025 08:33:25
%S A258991 0,8,3,6,7,3,1,1,3,0,1,6,4,9,5,3,6,1,6,1,4,8,9,0,4,3,6,5,4,2,3,8,7,7,
%T A258991 0,5,4,3,8,2,4,6,7,3,2,5,5,4,1,5,4,1,6,8,3,6,0,7,5,9,1,8,3,5,5,4,3,8,
%U A258991 1,9,1,2,7,1,4,5,6,2,4,0,1,1,9,9,6,0,7,2,6,9,1,9,7,6,9,7,6,6,4,2,6,0,3,7,6,9,7
%N A258991 Decimal expansion of the multiple zeta value (Euler sum) zetamult(4,4).
%H A258991 Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/MultivariateZetaFunction.html">Multivariate Zeta Function</a>
%H A258991 Wikipedia, <a href="https://en.wikipedia.org/wiki/Multiple_zeta_function">Multiple zeta function</a>
%F A258991 zetamult(4,4) = Sum_{m>=2} (Sum_{n=1..m-1} 1/(m^4*n^4)) = (1/2)*(zeta(4)^2 - zeta(8)).
%e A258991 0.08367311301649536161489043654238770543824673255415416836075918355438...
%t A258991 Join[{0}, RealDigits[(1/2)*(Zeta[4]^2 - Zeta[8]), 10, 106] // First]
%o A258991 (PARI) zetamult([4,4]) \\ _Charles R Greathouse IV_, Jan 21 2016
%o A258991 (PARI) (zeta(4)^2-zeta(8))/2 \\ _Charles R Greathouse IV_, Jan 20 2022
%Y A258991 Cf. A072691 (zetamult(1,1)), A197110 (zetamult(2,2)), A258983 (zetamult(3,2)), A258984 (4,2), A258985 (5,2), A258947 (6,2), A258986 (2,3), A258987 (3,3), A258988 (4,3), A258982 (5,3), A258989 (2,4), A258990 (3,4).
%K A258991 nonn,cons,easy
%O A258991 0,2
%A A258991 _Jean-François Alcover_, Jun 16 2015