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!)
A128413 Inverse of number triangle A128412. 3
1, 2, 1, 12, 8, 1, 80, 60, 12, 1, 560, 448, 112, 16, 1, 4032, 3360, 960, 180, 20, 1, 29568, 25344, 7920, 1760, 264, 24, 1, 219648, 192192, 64064, 16016, 2912, 364, 28, 1, 1647360, 1464320, 512512, 139776, 29120, 4480, 480, 32, 1, 12446720 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

First column is A069723.

LINKS

Table of n, a(n) for n=0..45.

FORMULA

Number triangle T(n,k)=if(k=0,2^n*(C(2n,n)/2+0^n/2),2^(n-k)*C(2n,n-k)); Column k has g.f. if(k=0,4x/(sqrt(1-8x)(1-sqrt(1-8x))),(1/sqrt(1-8x))*((1-4x-sqrt(1-8x))/(8x))^k);

EXAMPLE

Triangle begins

1,

2, 1,

12, 8, 1,

80, 60, 12, 1,

560, 448, 112, 16, 1,

4032, 3360, 960, 180, 20, 1,

29568, 25344, 7920, 1760, 264, 24, 1,

219648, 192192, 64064, 16016, 2912, 364, 28, 1

CROSSREFS

Cf. A128417.

Sequence in context: A257635 A085752 A074966 * A058843 A130559 A135256

Adjacent sequences:  A128410 A128411 A128412 * A128414 A128415 A128416

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Mar 02 2007

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 July 5 20:21 EDT 2020. Contains 335473 sequences. (Running on oeis4.)