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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A302699 G.f. A(x) satisfies: A(x) = 1 + x * A(x) * (A(x) + 3*x*A'(x)) / (A(x) + x*A'(x)). 1
1, 1, 3, 13, 71, 469, 3711, 35181, 398791, 5352149, 83650687, 1494274301, 29988083447, 666634964197, 16233361360559, 429237520044813, 12237655701598503, 374023408217062261, 12195222470567359071, 422440153967133458205, 15490152522612488256855, 599350023954941335582725, 24401304036660493806643215 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Compare to: C(x) = 1 + x*C(x) * (C(x) + 2*x*C'(x)) / (C(x) + x*C'(x)) holds when C(x) = 1 + x*C(x)^2 is a g.f. of the Catalan numbers (A000108).

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..300

FORMULA

G.f. A(x) satisfies:

(1) A(x) = 1 + x*A(x) * (A(x) + 3*x*A'(x)) / (A(x) + x*A'(x)).

(2) A(x) = 1/(1 - x*A(x)/(1 - x*A(x)/(1 - 2*x*A(x)/(1 - 3*x*A(x)/(1 - 4*x*A(x)/(1 - 5*x*A(x)/(1 - ...)))))), a continued fraction.

(3) A(x) = Series_Reversion( x - x^2*F(x) ) where F(x) = Sum_{n>=0} (2*n)!/(n!*2^n)*x^n (g.f. of the odd double factorials A001147).

EXAMPLE

G.f.: A(x) = 1 + x + 3*x^2 + 13*x^3 + 71*x^4 + 469*x^5 + 3711*x^6 + 35181*x^7 + 398791*x^8 + 5352149*x^9 + 83650687*x^10 + ...

RELATED SERIES.

A'(x)/A(x) = 1 + 5*x + 31*x^2 + 225*x^3 + 1891*x^4 + 18473*x^5 + 210939*x^6 + 2815137*x^7 + 43551715*x^8 + 770297385*x^9 + ...

A(x) + x*A'(x) = 1 + 2*x + 9*x^2 + 52*x^3 + 355*x^4 + 2814*x^5 + 25977*x^6 + 281448*x^7 + 3589119*x^8 + 53521490*x^9 + ...

PROG

(PARI) /* Differential equation: */

{a(n) = my(A=1); for(i=0, n, A = 1 + x*A*(A + 3*x*A')/(x*A +x^2*O(x^n))'); polcoeff(G=A, n)}

for(n=0, 30, print1(a(n), ", "))

(PARI) /* Continued fraction: */

{a(n) = my(A=1, CF = 1+x +x*O(x^n)); for(i=1, n, for(k=0, n, CF = 1/(1 - (n-k+1)*x*A*CF ) ); A=1/(1 - x*A*CF) ); polcoeff(A, n)}

for(n=0, 30, print1(a(n), ", "))

CROSSREFS

Cf. A001147, A112934.

Sequence in context: A192936 A000261 A111140 * A137983 A327677 A307005

Adjacent sequences:  A302696 A302697 A302698 * A302700 A302701 A302702

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 11 2018

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 07:11 EST 2020. Contains 332159 sequences. (Running on oeis4.)