A352398 Denominators of partial sums of the Madhava series for Pi/(2*sqrt(3)) = A093766.

1, 9, 45, 945, 25515, 280665, 3648645, 32837805, 186080895, 31819833045, 286378497405, 6586705440315, 98800581604725, 8002847109982725, 232082566189499025, 7194559551874469775, 21583678655623409325, 7194559551874469775, 2395788330774198435075, 21562094976967785915675

Offset: 0

Author

Wolfdieter Lang, Apr 07 2022

Keywords

• nonn
• frac
• easy

Comments

For a comment and references see A352397.

Crossrefs

Cf. A352397 (numerators).

Cf. A093766.

Programs

Mathematica

Denominator @ Accumulate @ Table[(-1)^j/((2*j + 1)*3^j), {j, 0, 20}] (* Amiram Eldar, Apr 08 2022 *)

PARI

a(n) = denominator(sum(j=0, n, (-1)^j/((2*j+1)*3^j))); \\ Michel Marcus, Apr 08 2022

Formula

a(n) = denominator(Sum_{j=0..n} (-1)^j/((2*j+1)*3^j)), for n >= 0.