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A157309 G.f. A(x) satisfies the condition that both A(x) and F(x) = A(x*F(x)) = o.g.f. of A157310 have zeros for every other coefficient after initial terms; g.f. of dual sequence A157308 satisfies the same condition. 3

%I

%S 1,1,0,-1,0,9,0,-176,0,5693,0,-272185,0,18043492,0,-1587355800,0,

%T 179258676373,0,-25305967691715,0,4370075849887361,0,

%U -906689353191842372,0,222613537277330398444,0,-63850898347335510126988

%N G.f. A(x) satisfies the condition that both A(x) and F(x) = A(x*F(x)) = o.g.f. of A157310 have zeros for every other coefficient after initial terms; g.f. of dual sequence A157308 satisfies the same condition.

%F Let F(x) = o.g.f. of A157310, then F(x) satisfies:

%F A(x) = Series_Reversion(x/F(x))/x;

%F A(x) = F(x/A(x));

%F F(x) = A(x*F(x));

%F where A157310 has zeros for every other term after initial [1,1,1].

%e G.f.: A(x) = 1 + x - x^3 + 9*x^5 - 176*x^7 + 5693*x^9 -+...

%e RELATED FUNCTIONS.

%e If F(x) = A(x*F(x)) then F(x) = o.g.f. of A157310:

%e A157310 = [1,1,1,0,-3,0,38,0,-947,0,37394,0,-2120190,0,...];

%e has zeros for every other coefficient after initial terms.

%e ...

%e O.g.f. A(x) has similar properties as o.g.f. of A157308:

%e A157308 = [1,1,-1,0,3,0,-38,0,947,0,-37394,0,2120190,0,...].

%o (PARI) {a(n)=local(A=[1, 1]); for(i=1, n, if(#A%2==1, A=concat(A, 0);); if(#A%2==0, A=concat(A, t); A[ #A]=-subst(Vec(x/serreverse(x*Ser(A)))[ #A], t, 0))); Vec(x/serreverse(x*Ser(A)))[n+1]}

%Y Cf. A157308, A157310, A157307, A157304, A157305.

%K sign

%O 0,6

%A _Paul D. Hanna_, Mar 11 2009

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Last modified September 17 18:12 EDT 2021. Contains 347489 sequences. (Running on oeis4.)