%I A098332
%S A098332 1,1,3,11,1,81,141,363,1791,479,13597,29877,54911,353807,223443,2539989,
%T A098332 6806529,8302527,73999299,73313931,489731841,1584548241,1110170163,
%U A098332 15812965611,21391839999,94696016481
%V A098332 1,1,-3,-11,1,81,141,-363,-1791,-479,13597,29877,-54911,-353807,-223443,
               2539989,
%W A098332 6806529,-8302527,-73999299,-73313931,489731841,1584548241,-1110170163,
               -15812965611,
%X A098332 -21391839999,94696016481
%N A098332 Expansion of 1/sqrt(1-2x+9x^2).
%C A098332 Central coefficients of (1+x-2x^2)^n. Binomial transform of 1/sqrt(1+8x^2), 
               or (1,0,-4,0,24,0,...). Binomial transform is A098336.
%D A098332 Tony D. Noe, On the Divisibility of Generalized Central Trinomial Coefficients, 
               Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.7.
%F A098332 E.g.f. : exp(x)BesselI(0, 2sqrt(-2)x); a(n)=sum{k=0..floor(n/2), binomial(n, 
               2k)binomial(2k, k)(-2)^k}; a(n)=sum{k=0..floor(n/2), binomial(n, 
               k)binomial(n-k, k)(-2)^k); a(n)=(-1)^n*sum{k=0..n, binomial(n, k)^2*(-2)^k}.
%Y A098332 Sequence in context: A051498 A092528 A069604 this_sequence A096663 A133369 
               A110123
%Y A098332 Adjacent sequences: A098329 A098330 A098331 this_sequence A098333 A098334 
               A098335
%K A098332 easy,sign
%O A098332 0,3
%A A098332 Paul Barry (pbarry(AT)wit.ie), Sep 03 2004