login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A185758 A diagonal of triangle A185755. 4
2, 15, 120, 1190, 14595, 215950, 3761310, 75550188, 1721103648, 43872089118, 1237592664451, 38282002057156, 1288537309627464, 46886217384094764, 1834003542264708444, 76744318019878844916, 3420833746251201921980 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A185755(n,k) equals the coefficient of x^n*y^k in the n-th iteration of x*(1+xy)/(1-x).

LINKS

Table of n, a(n) for n=1..17.

PROG

(PARI) {a(n)=local(A=x, G=x*(1+x*y)/(1-x)); for(i=1, n+1, A=subst(G, x, A+O(x^(n+2)))); polcoeff(polcoeff(A, n+1, x), n-1, y)}

CROSSREFS

Cf. A185755, A185756, A185757, A185759.

Sequence in context: A300910 A161937 A074621 * A052448 A168502 A127610

Adjacent sequences:  A185755 A185756 A185757 * A185759 A185760 A185761

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Feb 03 2011

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 November 13 21:28 EST 2019. Contains 329106 sequences. (Running on oeis4.)