OFFSET
1,1
FORMULA
Equals Product_{k>=1} (1 + 1/(3*k*(k - 1)/2 + 1)).
Equals Product_{k>=1} (1 + 1/A005448(k)).
EXAMPLE
3.4084379526884991250972568943042066986209221843076631...
MATHEMATICA
RealDigits[Cosh[Sqrt[13/3] Pi/2] Sech[Sqrt[5/3] Pi/2], 10, 120][[1]]
RealDigits[Product[(1 + 1/(3 k (k - 1)/2 + 1)), {k, 1, Infinity}], 10, 120][[1]]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Ilya Gutkovskiy, Jun 15 2019
STATUS
approved