%I A052928
%S A052928 0,0,2,2,4,4,6,6,8,8,10,10,12,12,14,14,16,16,18,18,20,20,22,22,24,24,26,
               26,
%T A052928 28,28,30,30,32,32,34,34,36,36,38,38,40,40,42,42,44,44,46,46,48,48,50,
%U A052928 50,52,52,54,54,56,56,58,58,60,60,62,62,64,64,66,66,68,68,70,70,72,72
%N A052928 The even numbers repeated.
%C A052928 a(n) is also the binary rank of the complete graph K(n) [From Alessandro 
               Cosentino (cosenal(AT)gmail.com), Feb 07 2009]
%C A052928 Its ordinal transform is A000034 [From Paolo P. Lava (ppl(AT)spl.at), 
               Jun 25 2009]
%D A052928 C. D. Godsil and G. Royle, Algebraic Graph Theory, Springer, 2001, pag.181 
               [From Alessandro Cosentino (cosenal(AT)gmail.com), Feb 07 2009]
%H A052928 INRIA Algorithms Project, <a href="http://algo.inria.fr/bin/encyclopedia?Search=ECSnb&argsearch=914">
               Encyclopedia of Combinatorial Structures 914</a>
%H A052928 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               WallisFormula.html">Wallis Formula</a>
%H A052928 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               RandomMatrix.html">Random Matrix</a>
%H A052928 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Legendre-GaussQuadrature.html">Legendre-Gauss Quadrature</a>
%F A052928 a(n)=2*Floor[n/2]. G.f.: 2/(-1+x)^2/(1+x).
%F A052928 Recurrence: {a(0)=2, a(n)+a(n+1)-4-2*n}. Also a(n) = n+3/2+1/2*(-1)^(-n)
%F A052928 a(n) = n + Sum{k=1..n, (-1)^k} - William A. Tedeschi (fynmun(AT)hotmail.com), 
               Mar 20 2008
%F A052928 a(n)=2*n-a(n-1)-4 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Nov 21 2009]
%e A052928 For n=2,a(2)=2*2-0-4=0; n=3,a(3)=2*3-0-4=2; n=4,a(4)=2*4-2-4=2;n=5,a(5)=2*5-2-4=4 
               [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 21 2009]
%p A052928 spec := [S,{S=Union(Sequence(Prod(Z,Z)),Prod(Sequence(Z),Sequence(Z)))},
               unlabeled]: seq(combstruct[count](spec,size=n), n=0..20);
%p A052928 a:=n->add(1+(-1)^j,j=1..n):seq(a(n),n=0..94);# [From Zerinvary Lajos 
               (zerinvarylajos(AT)yahoo.com), Dec 13 2008]
%Y A052928 Sequence in context: A061106 A161764 A131055 this_sequence A137501 A005186 
               A008642
%Y A052928 Adjacent sequences: A052925 A052926 A052927 this_sequence A052929 A052930 
               A052931
%K A052928 easy,nonn
%O A052928 0,3
%A A052928 encyclopedia(AT)pommard.inria.fr, Jan 25 2000
%E A052928 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 05 2000