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 A260659 #29 Jun 19 2024 09:28:27
%S A260659 2,80,3584,1760,745472,4456448,99614720,265289728,10905190400,
%T A260659 54492397568,1065151889408,1277752770560,96619584290816,
%U A260659 450799767388160,8321103999008768,19017153114013696,689613692941107200,3102980143258271744,55484347409204510720,30822635849723674624
%N A260659 Denominators of a BBP-like formula for 4*Pi/sqrt(27).
%C A260659 4*Pi/sqrt(27) = Sum_{n >= 0} (-1/8)^n*(2/(3*n+1)+1/(3*n+2)).
%H A260659 Paolo Xausa, <a href="/A260659/b260659.txt">Table of n, a(n) for n = 0..1000</a>
%H A260659 David H. Bailey, <a href="https://www.davidhbailey.com/dhbpapers/bbp-formulas.pdf">A Compendium of BBP-Type Formulas for Mathematical Constants</a>.
%H A260659 David Brink, <a href="https://www.researchgate.net/publication/283579663_Nilakantha's_accelerated_series_for_pi">Nilakantha's accelerated series for pi</a>, Acta Arith. 171 (2015), 293-308.
%F A260659 a(n) = denominator((-1/8)^n*(2/(3*n+1)+1/(3*n+2))).
%t A260659 A260659[n_] := Denominator[(-1/8)^n*(2/(3*n + 1) + 1/(3*n + 2))];
%t A260659 Array[A260659, 25, 0] (* _Paolo Xausa_, Jun 19 2024 *)
%o A260659 (PARI) a(n) = denominator((-1/8)^n*(2/(3*n+1)+1/(3*n+2))); \\ _Michel Marcus_, Nov 15 2015
%o A260659 (Magma) [Denominator((-1/8)^n*(2/(3*n+1)+1/(3*n+2))): n in [0..60]]; // _Vincenzo Librandi_, Nov 20 2015
%Y A260659 Cf. A073010, A260658 (numerators).
%K A260659 nonn,frac
%O A260659 0,1
%A A260659 _David Brink_, Nov 13 2015
%E A260659 More terms from _Michel Marcus_, Nov 15 2015