%I A085403
%S A085403 1,2,2,6,22,90,394,1806,8558,41586,206098,1037718,5293446,27297738,
%T A085403 142078746,745387038,3937603038,20927156706,111818026018,600318853926,
%U A085403 3236724317174,17518619320890,95149655201962,518431875418926,2832923350929742
%V A085403 1,-2,-2,-6,-22,-90,-394,-1806,-8558,-41586,-206098,-1037718,-5293446,
               -27297738,
%W A085403 -142078746,-745387038,-3937603038,-20927156706,-111818026018,-600318853926,
%X A085403 -3236724317174,-17518619320890,-95149655201962,-518431875418926,-2832923350929742
%N A085403 Expansion of (1-x+sqrt(1-6x+x^2))/2 in powers of x.
%C A085403 Series reversion of x(Sum_{k>=0} a(k)x^k) is x(Sum_{k>=0} A027307(k)x^k).
%F A085403 G.f.: (1-x+sqrt(1-6x+x^2))/2. (=1/g.f. A006318)
%F A085403 Given g.f. A(x), y=A(x)x satisfies 0=f(x, y) where f(x, y)=y(y-x)+(x+y)x^2 
               . - Michael Somos May 23 2005 */
%o A085403 (PARI) a(n)=polcoeff((1-x+sqrt(1-6*x+x^2+x*O(x^n)))/2,n)
%Y A085403 A minor variation of A006318. a(n)=-A006318(n-1), n>1.
%Y A085403 Sequence in context: A004077 A007985 A097090 this_sequence A112478 A138801 
               A069466
%Y A085403 Adjacent sequences: A085400 A085401 A085402 this_sequence A085404 A085405 
               A085406
%K A085403 sign
%O A085403 0,2
%A A085403 Michael Somos, Jun 28 2003