%I M1286 N0493 #17 Apr 26 2020 22:53:38
%S 2,4,14,128,3882,412736,151223522,189581406208,820064805806914,
%T 12419746847290729472,668590083306794321516802,
%U 129667782549203712117025325056,91624448643446654575608517356620802,238057970008583161105667221977375792447488
%N a(n) = 2 * Sum_{i=0..n} C(2^n-1, i).
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%D R. O. Winder, Enumeration of seven-argument threshold functions, IEEE Trans. Electron. Computers, 14 (1965), 315-.
%H T. D. Noe, <a href="/A001527/b001527.txt">Table of n, a(n) for n = 0..30</a>
%t Table[2*Sum[Binomial[2^n - 1, i], {i, 0, n}], {n, 0, 15}] (* _Harvey P. Dale_, Mar 27 2011 *)
%Y Equals 2 * A046855.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_