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 A216490 G.f. satisfies: A(x) = 1 + x*A(x)^2 + x^3*A(x)^5. 4
 1, 1, 2, 6, 21, 78, 302, 1210, 4979, 20913, 89284, 386308, 1690221, 7465594, 33243970, 149080710, 672682035, 3051859515, 13913105076, 63704186436, 292825392338, 1350782681404, 6251139672412, 29014088205700, 135029529235367, 629978080093921, 2945889534054758 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA G.f. satisfies: A(x) = 1/A(-x*A(x)^3); note that the Catalan function C(x) = 1 + x*C(x)^2 also satisfies this condition: C(x) = 1/C(-x*C(x)^3). Recurrence: 8*n*(2*n+1)*(4*n+1)*(4*n+3)*(18857*n^5 - 123695*n^4 + 307075*n^3 - 357745*n^2 + 193668*n - 38880)*a(n) = (29662061*n^9 - 194572235*n^8 + 475490846*n^7 - 510273230*n^6 + 169643069*n^5 + 97131085*n^4 - 80249496*n^3 + 9135180*n^2 + 4205520*n - 777600)*a(n-1) - 3*(13463898*n^9 - 108514077*n^8 + 347609938*n^7 - 547442512*n^6 + 395255792*n^5 - 25515983*n^4 - 129824028*n^3 + 55362252*n^2 + 3442320*n - 3888000)*a(n-2) + 5*(5*n - 12)*(5*n - 11)*(5*n - 9)*(5*n - 8)*(18857*n^5 - 29410*n^4 + 865*n^3 + 9880*n^2 - 1092*n - 720)*a(n-3). - Vaclav Kotesovec, Sep 10 2013 a(n) ~ c*d^n/n^(3/2), where d = 1/768*((2775409885 + 28964352 * sqrt(8502))^(2/3) + 1573*(2775409885 + 28964352 * sqrt(8502))^(1/3) + 829273)/(2775409885 + 28964352 * sqrt(8502))^(1/3) = 4.952774592083496... is the root of the equation -3125 + 2142*d - 1573*d^2 + 256*d^3 = 0 and c = 0.3472109760934755295223550512446412412267... - Vaclav Kotesovec, Sep 10 2013 EXAMPLE G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 21*x^4 + 78*x^5 + 302*x^6 + 1210*x^7 +... Related expansions: A(x)^2 = 1 + 2*x + 5*x^2 + 16*x^3 + 58*x^4 + 222*x^5 + 880*x^6 + 3588*x^7 +... A(x)^5 = 1 + 5*x + 20*x^2 + 80*x^3 + 330*x^4 + 1391*x^5 + 5950*x^6 +... Given (1) A(x) = 1 + x*A(x)^2 + x^3*A(x)^5, suppose (2) A(x) = 1/A(-x*A(x)^3), then substituting x in (1) with -x*A(x)^3 yields: 1/A(x) = 1 - x*A(x)^3/A(x)^2 - x^3*A(x)^9/A(x)^5, which illustrates that (2) is consistent with (1). MATHEMATICA nmax=20; aa=ConstantArray[0, nmax]; aa[[1]]=1; Do[AGF=1+Sum[aa[[n]]*x^n, {n, 1, j-1}]+koef*x^j; sol=Solve[Coefficient[1+x*AGF^2+x^3*AGF^5-AGF, x, j]==0, koef][[1]]; aa[[j]]=koef/.sol[[1]], {j, 2, nmax}]; Flatten[{1, aa}] (* Vaclav Kotesovec, Sep 10 2013 *) PROG (PARI) {a(n)=local(A=1+x); for(i=1, n, A=1+x*A^2+x^3*A^5 +x*O(x^n)); polcoeff(A, n)} for(n=0, 30, print1(a(n), ", ")) CROSSREFS Cf. A112806. Sequence in context: A254316 A279562 A054515 * A150190 A150191 A150192 Adjacent sequences:  A216487 A216488 A216489 * A216491 A216492 A216493 KEYWORD nonn AUTHOR Paul D. Hanna, Sep 07 2012 STATUS approved

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Last modified June 24 00:22 EDT 2021. Contains 345403 sequences. (Running on oeis4.)