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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A210239 Triangle, read by rows, given by (2, -1, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. 0
1, 2, 2, 2, 5, 3, 2, 9, 12, 5, 2, 13, 28, 25, 8, 2, 17, 52, 74, 50, 13, 2, 21, 84, 167, 177, 96, 21, 2, 25, 124, 320, 470, 397, 180, 34, 2, 29, 172, 549, 1041, 1211, 850, 331, 55, 2, 33, 228, 870, 2034, 3042, 2928, 1758, 600, 89 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..54.

FORMULA

G.f.: (1+x+y*x)/(1-x-y*x-y*x^2-y^2*x^2).

T(n,k) = T(n-1,k) + T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2), T(0,0) = 1, T(1,0) = T(1,1) = 2 and T(n,k) = 0 if k<0 or if k>n.

Sum_{k, 0<=k<=n} T(n,k)*x^k = A122803(n), A000007(n), A040000(n), A026150(n+1) for x = -2, -1, 0, 1 respectively.

T(n,n) = Fibonacci(n+2) = A000045(n+2), T(n+1,n) = A067331(n).

EXAMPLE

Triangle begins :

1

2, 2

2, 5, 3

2, 9, 12, 5

2, 13, 28, 25, 8

2, 17, 52, 74, 50, 13

2, 21, 84, 167, 177, 96, 21

2, 25, 124, 320, 470, 397, 180, 34

CROSSREFS

Cf. A000045, A026150, A112087 (3rd column, n>2).

Sequence in context: A228917 A061311 A174960 * A115253 A154429 A174577

Adjacent sequences:  A210236 A210237 A210238 * A210240 A210241 A210242

KEYWORD

easy,nonn,tabl

AUTHOR

Philippe Deléham, Mar 19 2012

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 October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)