OFFSET
0,1
LINKS
Eric Weisstein's World of Mathematics, Kelvin Functions.
Wikipedia, Kelvin functions.
FORMULA
Equals Re(BesselJ(0, 2*exp(3*Pi*i/4))).
EXAMPLE
0.75173418271380822855099890123074657595958657660729200273884...
MAPLE
evalf(Sum((-1)^k/(2*k)!^2, k=0..infinity), 120);
MATHEMATICA
RealDigits[KelvinBer[0, 2], 10, 120][[1]]
RealDigits[Re[Hypergeometric0F1Regularized[1, I]], 10, 120][[1]]
RealDigits[HypergeometricPFQ[{}, {1/2, 1/2, 1}, -1/16], 10, 120][[1]] (* Vaclav Kotesovec, Jul 19 2021 *)
PROG
(PARI) sumalt(k=0, (-1)^k/(2*k)!^2)
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Vaclav Kotesovec, Sep 10 2020
STATUS
approved