OFFSET
0,1
COMMENTS
The constant xi = Sum_{k>=0} binomial(L*k+1, k)*A^(-L*k-1)/(L*k+1) is a positive real root of the equation xi^L - A*xi + 1 = 0 where A > 1 and L > 0 (see Exercise n. 1 at p. 188 in Wilf). Here A = L = 4.
LINKS
Herbert S. Wilf, Generatingfunctionology, 2nd edn., Academic Press, NY, 1994, p. 188.
FORMULA
Equals Sum_{k>=0} binomial(4*k+1, k)*4^(-4*k-1)/(4*k+1).
Minimal polynomial: x^4 - 4*x + 1.
EXAMPLE
0.2509921574904908514198343861632649343605775309...
MATHEMATICA
RealDigits[HypergeometricPFQ[{1/4, 1/2, 3/4}, {2/3, 4/3}, 1/27]/4, 10, 100][[1]]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Stefano Spezia, Dec 23 2025
STATUS
approved
