OFFSET
1,3
FORMULA
Equals (18*e^(1/4) + sqrt(Pi)*erfi(1/2))/(16*e^(1/4)).
Equals 2*1F1(3;3/2;-1/4) . - R. J. Mathar, Aug 02 2024
EXAMPLE
1.17805454793775278699175529406120869638705368466996...
MATHEMATICA
s = Sum[(-1)^k (k + 2)!/(2 k+1)!, {k, 0, Infinity}]
d = N[s, 100]
First[RealDigits[d]]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Clark Kimberling, Apr 28 2024
STATUS
approved