%I A000116 M1156 N0440
%S A000116 1,2,4,8,20,56,180,596,2068,7316,26272,95420,349716,1290872,4794088,
%T A000116 17896832,67110932,252648992,954444608,3616828364,13743921632,52357746896,
%U A000116 199911300472,764877836468,2932031358484,11258999739560,43303843861744,
               166799988689300
%N A000116 Number of even sequences with period 2n (bisection of A000013).
%D A000116 E. N. Gilbert and J. Riordan, Symmetry types of periodic sequences, Illinois 
               J. Math., 5 (1961), 657-665.
%D A000116 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000116 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%Y A000116 Cf. A000013, A026119.
%Y A000116 Sequence in context: A123611 A082279 A113180 this_sequence A006407 A100447 
               A112278
%Y A000116 Adjacent sequences: A000113 A000114 A000115 this_sequence A000117 A000118 
               A000119
%K A000116 nonn,easy,nice
%O A000116 0,2
%A A000116 N. J. A. Sloane (njas(AT)research.att.com).
%E A000116 More terms from David W. Wilson (davidwwilson(AT)comcast.net) Jan 13 
               2000.