OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: AGM(1, 1-8x).
a(n) ~ -Pi * 2^(3*n-1) / (n * log(n)^2) * (1 - (2*gamma + 4*log(2))/log(n) + (3*gamma^2 + 12*log(2)*gamma + 12*log(2)^2 - Pi^2/2) / log(n)^2), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Sep 29 2019
MATHEMATICA
CoefficientList[Series[1/Hypergeometric2F1[1/2, 1/2, 1, 16*x*(1 - 4*x)], {x, 0, 20}], x] (* Vaclav Kotesovec, Jan 13 2019 *)
CoefficientList[Series[Pi*(1 - 4*x)/(2*EllipticK[1/(1 - 1/(4*x))^2]), {x, 0, 20}], x] (* Vaclav Kotesovec, Jan 13 2019 *)
PROG
(PARI) a(n)=if(n<0, 0, polcoeff(agm(1, 1-8*x+x*O(x^n)), n))
CROSSREFS
KEYWORD
sign
AUTHOR
Roland Bacher, Apr 20 2001
EXTENSIONS
Edited by Michael Somos, Jul 19, 2002
STATUS
approved