A084243 Decimal expansion of c = Product_{k>=1} (1 + 1/k^2)^2.

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

Offset: 2

Author

Benoit Cloitre, Jun 21 2003

Keywords

• cons
• nonn

Examples

			13.513548803146862731723815...
		

References

• Bruce C. Berndt, Ramanujan Notebook part II, Integral and asymptotic expansions, Springer Verlag, p. 230, entry 27.

Programs

Mathematica

Sinh[Pi]^2/Pi^2 // RealDigits[#, 10, 105]& // First (* Jean-François Alcover, Mar 04 2013 *)

PARI

(cosh(2*Pi)-1)/2/Pi^2

Formula

Equals (cosh(2*Pi)-1)/(2*Pi^2).

Equals (sinh(Pi)/Pi)^2. - Bernard Schott, Jan 04 2021