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

0,2

Comments

For a comment and references see A352397.

Links

Table of n, a(n) for n=0..19.

Formula

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

Mathematica

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

Prog

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

Crossrefs

Cf. A352397 (numerators).

Cf. A093766.

Sequence in context: A177742 A322892 A355175 * A261847 A050909 A333306

Adjacent sequences: A352395 A352396 A352397 * A352399 A352400 A352401

Keyword

nonn,frac,easy

Author

Wolfdieter Lang, Apr 07 2022

Status

approved