A196869 G.f. A(x) satisfies: A(x)^3 + A(-x)^3 = 2 and A(x)^2 - A(-x)^2 = 24*x.

1, 6, -36, 216, -2592, 23328, -311040, 3265920, -45349632, 517321728, -7336562688, 88159684608, -1266403590144, 15771513618432, -228509902503936, 2921050338066432, -42583086769766400, 555279063084564480, -8132204141176946688, 107718176292801085440

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Example

G.f.: A(x) = 1 + 6*x - 36*x^2 + 216*x^3 - 2592*x^4 + 23328*x^5 +...
where
A(x)^2 = 1 + 12*x - 36*x^2 - 1296*x^4 - 108864*x^6 - 12317184*x^8 +...
A(x)^3 = 1 + 18*x - 432*x^3 - 23328*x^5 - 2239488*x^7 - 272097792*x^9 +...

Prog

(PARI) {a(n)=local(A=[1, 6]); for(k=2, n, A=concat(A, 0); if(k%2==1, A[#A]=-Vec(Ser(A)^2)[#A]/2, A[#A]=-Vec(Ser(A)^3)[#A]/3)); A[n+1]}

Crossrefs

Cf. A196868, A193618, A193619, A196864, A196865, A196866, A196867.

Sequence in context: A238936 A097681 A050736 * A172489 A033142 A082309

Adjacent sequences: A196866 A196867 A196868 * A196870 A196871 A196872

Keyword

sign

Author

Paul D. Hanna, Oct 06 2011

Status

approved