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A324620 G.f. A(x) = Sum_{n>=0} x^n*(A(x)^n + sqrt(2))^n/(1 + sqrt(2)*x*A(x)^n)^(n+1). 0
1, 1, 2, 3, 7, 22, 92, 440, 2281, 12493, 71765, 430651, 2693870, 17539117, 118715136, 834501419, 6086215582, 46008381159, 360118132277, 2915376645033, 24382943109124, 210428145134993, 1871657093564422, 17137046392867008, 161334811357004021, 1559974013680482615, 15475431343550867360, 157351220236056642597, 1638298847460905532116, 17451514257450951873260, 190036890804241449007404, 2113879533614295483104495 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..31.

FORMULA

G.f. A(x) satisfies:

(1) A(x) = Sum_{n>=0} x^n*(A(x)^n + sqrt(2))^n / (1 + sqrt(2)*x*A(x)^n)^(n+1).

(2) A(x) = Sum_{n>=0} x^n*(A(x)^n - sqrt(2))^n / (1 - sqrt(2)*x*A(x)^n)^(n+1).

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 3*x^3 + 7*x^4 + 22*x^5 + 92*x^6 + 440*x^7 + 2281*x^8 + 12493*x^9 + 71765*x^10 + 430651*x^11 + 2693870*x^12 + ...

Let q = sqrt(2), then

A(x) = 1/(1 + q*x*A(x)) + x*(A(x) + q)/(1 + q*x*A(x))^2 + x^2*(A(x)^2 + 1)^2 / (1 + q*x*A(x)^2)^3 + x^3*(A(x)^3 + 1)^3/(1 + q*x*A(x)^3)^4 + x^4*(A(x)^4 + 1)^4 / (1 + q*x*A(x)^4)^5 + x^5*(A(x)^5 + 1)^5/(1 + q*x*A(x)^5)^6 + ...

also

A(x) = 1/(1 - q*x*A(x)) + x*(A(x) - q)/(1 - q*x*A(x))^2 + x^2*(A(x)^2 - 1)^2 / (1 - q*x*A(x)^2)^3 + x^3*(A(x)^3 - 1)^3/(1 - q*x*A(x)^3)^4 + x^4*(A(x)^4 - 1)^4 / (1 - q*x*A(x)^4)^5 + x^5*(A(x)^5 - 1)^5/(1 - q*x*A(x)^5)^6 + ...

PROG

(PARI) {a(n) = my(A=[1, 1]); for(i=0, n, A = concat(A, 0);

A[#A] = polcoeff( sum(n=0, #A+1, x^n*(Ser(A)^n + sqrt(2))^n/(1 + sqrt(2)*x*Ser(A)^n)^(n+1) ), #A-1)); round( polcoeff(Ser(A), n) )}

for(n=0, 40, print1(a(n), ", "))

CROSSREFS

Cf. A324618, A324619.

Sequence in context: A094062 A038159 A077210 * A151908 A072214 A233535

Adjacent sequences:  A324617 A324618 A324619 * A324621 A324622 A324623

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 12 2019

STATUS

approved

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Last modified June 6 17:20 EDT 2020. Contains 334829 sequences. (Running on oeis4.)