The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A264412 G.f. A(x) satisfies: A(x)^2 = A(x^2) + 6*x. 8
 1, 3, -3, 9, -33, 126, -513, 2214, -9876, 45045, -209493, 990198, -4741191, 22946247, -112079214, 551793303, -2735330190, 13641353118, -68394016548, 344539469889, -1743035351958, 8851923849123, -45110440515753, 230615809867476, -1182376529280117, 6078184963674498, -31322206517658453, 161774639164275552, -837290923919381322 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Paul D. Hanna, Table of n, a(n) for n = 0..300 FORMULA Given g.f. A(x), let G(x) denote the g.f. of A264224, then: (1) G( x/(A(x)^2 - 4*x) ) = x, (2) G( x/(A(x^2) + 2*x) ) = x, (3) A(G(x))^2 = (1+4*x) * G(x)/x, (4) A(G(x)^2) = (1-2*x) * G(x)/x, where G(x)^2 = G( x^2/(1-4*x) ). a(n) ~ c * (-1)^(n+1) * d^n / n^(3/2), where d = 5.46806882358680646837..., c = 0.268849330049069376... . - Vaclav Kotesovec, Nov 18 2015 EXAMPLE G.f.: A(x) = 1 + 3*x - 3*x^2 + 9*x^3 - 33*x^4 + 126*x^5 - 513*x^6 + 2214*x^7 - 9876*x^8 + 45045*x^9 +... where A(x)^2 = 1 + 6*x + 3*x^2 - 3*x^4 + 9*x^6 - 33*x^8 + 126*x^10 - 513*x^12 + 2214*x^14 - 9876*x^16 + 45045*x^18 +... so that A(x)^2 = A(x^2) + 6*x. Let G(x) = Series_Reversion( x / (A(x^2) + 2*x) ), then G(x) = x + 2*x^2 + 7*x^3 + 26*x^4 + 103*x^5 + 422*x^6 + 1774*x^7 + 7604*x^8 + 33109*x^9 + 146042*x^10 +...+ A264224(n)*x^n +... such that G(x)^2 = G( x^2/(1-4*x) ) and A(G(x))^2 = (1+4*x) * G(x)/x. PROG (PARI) {a(n) = my(A=1); for(i=1, n, A = sqrt( subst(A, x, x^2) + 6*x +x*O(x^n))); polcoeff(A, n)} for(n=0, 30, print1(a(n), ", ")) CROSSREFS Cf. A271930, A264224, A264413, A264414, A264415. Sequence in context: A327712 A257611 A268617 * A202889 A257620 A032086 Adjacent sequences:  A264409 A264410 A264411 * A264413 A264414 A264415 KEYWORD sign AUTHOR Paul D. Hanna, Nov 12 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 6 08:22 EDT 2020. Contains 336228 sequences. (Running on oeis4.)