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A143564 G.f. satisfies: A(x) = 1 + x*A(x)^4/A(-x)^3. 1
1, 1, 7, 31, 273, 1697, 16471, 116159, 1186081, 8928193, 94017703, 736522975, 7917810225, 63722594657, 695248655095, 5705316231551, 62944217175617, 524183926274433, 5833380674885959, 49141433498848159, 550674827214221137 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..20.

FORMULA

G.f. satisfies: A(x) + A(-x) = 1 + (1+x^2)*A(x)*A(-x).

G.f.: A(x) = G(x)/(1+x^2) where G(x) = 1 + x*G(x)^4/G(-x)^4 is the g.f. of A143557.

EXAMPLE

G.f. A(x) = 1 + x + 7*x^2 + 31*x^3 + 273*x^4 + 1697*x^5 +...

A(x)*A(-x) = 1 + 13*x^2 + 533*x^4 + 32409*x^6 + 2339753*x^8 +...

PROG

(PARI) {a(n)=local(A=1+x*O(x^n)); for(i=0, n, A=1+x*A^4/subst(A^3, x, -x)); polcoeff(A, n)}

CROSSREFS

Cf. A143557, A143562.

Sequence in context: A094711 A333735 A221875 * A253596 A298958 A153028

Adjacent sequences:  A143561 A143562 A143563 * A143565 A143566 A143567

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Aug 24 2008

STATUS

approved

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Last modified April 7 04:08 EDT 2020. Contains 333292 sequences. (Running on oeis4.)