A256324 - OEIS

%I #10 Feb 16 2025 08:33:25

%S 30,840,3780,3520,750750,98280,2099160,7441920,10665270,5313000,

%T 119390700,3931200,40139190,18501420,313038000,241274880,2175918570,

%U 266493240,1535455740,3258024000,1007504190,172657320,16812360600,3742502400

%N a(n) = denominator of (1/n^3)*(-1/(n+1) + 16/(n+2) + 3/(4*(2*n+1)) - 81/(4*(2*n+3))), term of a BBP-type series representation of zeta(3) by V. Adamchik and S. Wagon.

%H Victor Adamchik and Stan Wagon, <a href="http://www.cs.cmu.edu/~adamchik/articles/pi/pi.htm">Pi: A 2000-Year Search Changes Direction</a>

%H David Bailey, Peter Borwein, Simon Plouffe, <a href="http://www.cs.cmu.edu/~adamchik/articles/pi/pi.htm">On the rapid computation of various polylogarithmic constants</a>

%H Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/BBP-TypeFormula.html">BBP-Type Formula</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Bailey%E2%80%93Borwein%E2%80%93Plouffe_formula">Bailey-Borwein-Plouffe formula</a>

%t a[n_] := Denominator[(1/n^3)*(-1/(n+1) + 16/(n+2) + 3/(4*(2*n+1)) - 81/(4*(2*n+3)))]; Table[a[n], {n, 1, 40}]

%Y Cf. A002117, A256323 (numerators).

%K nonn,frac,easy

%O 1,1

%A _Jean-François Alcover_, Mar 24 2015