%I A086456
%S A086456 1,1,2,6,22,90,394,1806,8558,41586,206098,1037718,5293446,27297738,
%T A086456 142078746,745387038,3937603038,20927156706,111818026018,600318853926,
%U A086456 3236724317174,17518619320890,95149655201962
%V A086456 1,-1,-2,-6,-22,-90,-394,-1806,-8558,-41586,-206098,-1037718,-5293446,
               -27297738,
%W A086456 -142078746,-745387038,-3937603038,-20927156706,-111818026018,-600318853926,
%X A086456 -3236724317174,-17518619320890,-95149655201962
%N A086456 Expansion of (1+x+sqrt(1-6x+x^2))/2 in powers of x.
%C A086456 Series reversion of x(Sum_{k>=0} a(k)x^k) is x(Sum_{k>=0} A003168(k)x^k).
%C A086456 G.f. A(x)=Sum_{k>=0} a(k)x^k satisfies 0=2x-(x+1)*A(x)+A(x)^2.
%F A086456 G.f.: (1+x+sqrt(1-6x+x^2))/2. (=1/g.f. A001003)
%o A086456 (PARI) a(n)=polcoeff((1+x+sqrt(1-6*x+x^2+x*O(x^n)))/2,n)
%Y A086456 A minor variation of A006318. a(n)=-A006318(n-1), n>0. a(n)=A085403(n), 
               n>1.
%Y A086456 Sequence in context: A165523 A049126 A049134 this_sequence A006318 A155069 
               A103137
%Y A086456 Adjacent sequences: A086453 A086454 A086455 this_sequence A086457 A086458 
               A086459
%K A086456 sign
%O A086456 0,3
%A A086456 Michael Somos, Jul 20 2003