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%I #18 Jun 01 2023 01:58:16
%S 5,0,7,9,2,2,0,2,0,8,6,6,3,6,7,8,3,3,6,0,4,3,6,8,7,9,5,6,7,8,2,0,2,1,
%T 0,7,4,8,3,2,3,9,7,3,4,5,7,0,8,3,5,9,7,7,4,2,8,4,8,2,4,3,7,9,1,6,8,7,
%U 4,5,9,0,9,3,2,9,1,9,9,0,6,9,4,7,0,1,5,4,5,4,9,0,2,3,3,4,9,0,3,6,1,0,2,8,8
%N Decimal expansion of c = Product_{k>=1} (1 + 1/t(k)) where t(k) = k(k+1)/2 is the k-th triangular number.
%D Bruce C. Berndt, Ramanujan Notebook part II, Infinite series, Springer Verlag, 1989, p. 241.
%F Equals ((1/2)/Pi)*cosh(Pi/2*sqrt(7)).
%e 5.07922020866367833604368795...
%t RealDigits[Cosh[Pi/2*Sqrt[7]]/(2*Pi), 10, 120][[1]] (* _Amiram Eldar_, Jun 01 2023 *)
%o (PARI) 1/2/Pi*cosh(Pi/2*sqrt(7))
%Y Cf. A000217.
%K cons,nonn
%O 1,1
%A _Benoit Cloitre_, Jun 21 2003
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