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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A143918 G.f. A(x) satisfies: A(x) = 1/(1-x)^2 + x^2*A'(x). 0
1, 2, 5, 14, 47, 194, 977, 5870, 41099, 328802, 2959229, 29592302, 325515335, 3906184034, 50780392457, 710925494414, 10663882416227, 170622118659650, 2900576017214069, 52210368309853262, 991996997887211999 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

FORMULA

a(n) = 3*floor(e*(n-1)!)-1, n>1 [From Gary Detlefs, Jun 10 2010]

EXAMPLE

G.f.: A(x) = 1 + 2*x + 5*x^2 + 14*x^3 + 47*x^4 + 194*x^5 + 977*x^6 +...

x^2*A'(x) = 2*x^2 + 10*x^3 + 42*x^4 + 188*x^5 + 970*x^6 + 5862*x^7 +...

MATHEMATICA

a=2; lst={}; Do[a=n+a*(n-2); AppendTo[lst, a], {n, 0, 3*4!}]; lst [From Vladimir Joseph Stephan Orlovsky, Mar 16 2010]

PROG

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

CROSSREFS

Sequence in context: A096402 A007268 A109156 * A129867 A119841 A149905

Adjacent sequences:  A143915 A143916 A143917 * A143919 A143920 A143921

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 05 2008

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified August 27 13:20 EDT 2014. Contains 246135 sequences.