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!)
A181136 G.f.: A(x) = Sum_{n>=0} x^n/[Sum_{k=0..n} C(n,k)^3*(-x)^k]. 1
1, 1, 2, 10, 92, 1264, 26138, 753322, 28451978, 1385043022, 84971475986, 6393154081582, 580295829204452, 62818032904371952, 8005929383232314294, 1187186361565313907994, 203034917331580351972520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Compare the g.f. of this sequence to the identity:

(1-x)/(1-2*x) = Sum_{n>=0} x^n/[Sum_{k=0..n} C(n,k)*(-x)^k].

LINKS

Robert Israel, Table of n, a(n) for n = 0..248

FORMULA

G.f.: Sum_{n>=0} x^n/hypergeom([-n,-n,-n],[1,1],x). - Robert Israel, Dec 24 2017

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 10*x^3 + 92*x^4 + 1264*x^5 +...

which equals the series:

A(x) = 1 + x/(1-x) + x^2/(1-2^3*x+x^2) + x^3/(1-3^3*x+3^3*x^2-x^3) + x^4/(1-4^3*x+6^3*x^2-4^3*x^3+x^4) + x^5/(1-5^3*x+10^3*x^2-10^3*x^3+5^3*x^4-x^5) +...

MAPLE

G:= add(x^n/hypergeom([-n, -n, -n], [1, 1], x), n=0..50):

S:= series(G501, x, 51):

seq(coeff(S, x, n), n=0..50); # Robert Israel, Dec 24 2017

PROG

(PARI) {a(n)=polcoeff(sum(m=0, n, x^m/sum(k=0, m, binomial(m, k)^3*(-x)^k+x*O(x^n))), n)}

CROSSREFS

Cf. A178324.

Sequence in context: A095937 A277380 A108528 * A182952 A108209 A111773

Adjacent sequences:  A181133 A181134 A181135 * A181137 A181138 A181139

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jan 25 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 August 7 06:02 EDT 2020. Contains 336274 sequences. (Running on oeis4.)