A258232 - OEIS

A258232

Decimal expansion of Integral_{x=0..1} Product_{k>=1} (1-x^k) dx.

3, 6, 8, 4, 1, 2, 5, 3, 5, 9, 3, 1, 4, 3, 3, 6, 5, 2, 3, 2, 1, 3, 1, 6, 5, 9, 7, 3, 2, 7, 8, 5, 1, 0, 1, 5, 0, 1, 4, 2, 4, 1, 3, 0, 3, 9, 2, 8, 8, 1, 9, 9, 6, 8, 3, 0, 3, 6, 1, 5, 8, 0, 6, 6, 8, 2, 8, 1, 4, 7, 3, 0, 0, 8, 8, 9, 0, 3, 4, 3, 9, 2, 9, 8, 9, 0, 6, 3, 4, 4, 2, 4, 2, 4, 1, 4, 9, 9, 2, 1, 7, 6, 7, 1, 2, 8

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OFFSET

0,1

REFERENCES

József Sándor and Borislav Crstici, Handbook of Number theory II, Kluwer Academic Publishers, 2004, Chapter 4, p. 424.

LINKS

Table of n, a(n) for n=0..105.

Jonathan M. Borwein and Peter B. Borwein, Strange series and high precision fraud, The American Mathematical Monthly, Vol. 99, No. 7 (1992), pp. 622-640; alternative link.

Martin Klazar, What is an answer? - remarks, results and problems on PIO formulas in combinatorial enumeration, part I, arXiv:1808.08449 [math.CO], 2018.

Vaclav Kotesovec, The integration of q-series.

H. F. Sandham, Problem 4614, The American Mathematical Monthly, Vol. 61, No. 10 (1954), p. 718; Definite Integral of an Infinite Product, Solution to Problem 4614 by T. F. Mulcrone, ibid., Vol. 63, No. 2 (1956), pp. 127-128.

FORMULA

Equals 8*Pi*sqrt(3/23) * sinh(sqrt(23)*Pi/6) / (2*cosh(sqrt(23)*Pi/3) - 1).

From Amiram Eldar, Feb 04 2024: (Start)

Equals 2 * Sum_{k=-oo..oo} (-1)^k/(3*k^2 + k + 2).

Equals Sum_{k>=0} (-1)^A000120(k)/(A029931(k)+1) (Borwein and Borwein, 1992). (End)

Equals 4 * sqrt(3/23) * Pi * sinh(sqrt(23)*Pi/3)/cosh(sqrt(23)*Pi/2) (Sandham, 1954). - Amiram Eldar, Apr 08 2026

EXAMPLE

0.3684125359314336523213165973278510150142413039288199683036158...

MAPLE

evalf(8*sqrt(3/23)*Pi*sinh(sqrt(23)*Pi/6)/(2*cosh(sqrt(23)*Pi/3)-1), 123);

# Alternative:

evalf(Sum((-1)^n/((3*n-1)*n/2 + 1), n=-infinity..infinity), 123);

MATHEMATICA

RealDigits[N[8*Sqrt[3/23]*Pi*Sinh[Sqrt[23]*Pi/6] / (2*Cosh[Sqrt[23]*Pi/3]-1), 120]][[1]]

PROG

(PARI) 8*Pi*sqrt(3/23) * sinh(sqrt(23)*Pi/6) / (2*cosh(sqrt(23)*Pi/3) - 1) \\ Michel Marcus, Nov 28 2018

CROSSREFS

Cf. A000120, A010815, A029931, A242168, A258229, A258230, A258408.

Cf. A258406 (m=2), A258407 (m=3), A258404 (m=4), A258405 (m=5).

Sequence in context: A108369 A377041 A010621 * A296568 A294095 A306633

Adjacent sequences: A258229 A258230 A258231 * A258233 A258234 A258235

KEYWORD

nonn,cons

AUTHOR

Vaclav Kotesovec, May 24 2015

STATUS

approved