(MAGMAMagma) [n : n in [0..150] | n mod 8 in [2, 3, 5, 6]]; // Wesley Ivan Hurt, May 26 2016
OEIS Server: https://oeis.org/edit/global/2944
reviewed
approved
proposed
editing
Sum_{n>=1} (-1)^(n+1)/a(n) = (2-sqrt(2))*Pi/8. - Amiram Eldar, Dec 25 2021
E.g.f.: (4 + sin(x) - cos(x) + (4*x - 1)*sinh(x) + (4*x - 3)*cosh(x))/2. - Ilya Gutkovskiy, May 27 2016