OFFSET
1,2
LINKS
M. Abramowitz and I. A. Stegun, Handbook of Mathematical functions, Chapter 9.6.
Eric Weisstein's World of Mathematics, Modified Bessel Function of the First Kind.
FORMULA
I_0(1) = Sum_{k>=0} 1/(4^k*k!^2) = Sum_{k>=0} 1/A002454(k).
Equals (1/Pi)*Integral_{t=0..Pi} exp(cos(t)) dt.
Equals BesselJ(0,i). - Jianing Song, Sep 18 2021
From Amiram Eldar, Jul 09 2023: (Start)
Equals exp(-1) * Sum_{k>=0} binomial(2*k,k)/(2^k*k!).
Equals e * Sum_{k>=0} (-1/2)^k * binomial(2*k,k)/k!. (End)
EXAMPLE
1.26606587775200833559824462521471753760767031135496...
MAPLE
BesselI(0, 1) ; evalf(%) ;
MATHEMATICA
RealDigits[BesselJ[0, I], 10, 120][[1]] (* Amiram Eldar, Jun 15 2023 *)
PROG
(PARI) besseli(0, 1) \\ Charles R Greathouse IV, Feb 19 2014
CROSSREFS
KEYWORD
AUTHOR
R. J. Mathar, Oct 08 2011
STATUS
approved