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!)
A108361 Diagonal sums of number triangle A108359. 2
1, 1, 2, 4, 7, 13, 25, 47, 90, 172, 329, 629, 1202, 2294, 4374, 8330, 15847, 30115, 57172, 108434, 205473, 389019, 735927, 1391121, 2627720, 4960134, 9356707, 17639323, 33234036, 62580444, 117776828, 221542596, 416524573, 782743029 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..33.

Index entries for linear recurrences with constant coefficients, signature (3,0,-4,-2,2,4,0,-1,-1).

FORMULA

a(n) = sum{k=0..floor(n/2)} ( sum{j=0..n-2k} C(k, j) * C(n-k-j, k) * floor((j+2)/2) ).

Empirical g.f.: (x^2+x-1)^2 / ((x-1)^2*(x+1)*(x^3+x^2+x-1)^2). - Colin Barker, Sep 26 2014

MAPLE

A108361:=n->add(add(binomial(k, j)*binomial(n-k-j, k)*floor((j+2)/2), j=0..n-2*k), k=0..floor(n/2)): seq(A108361(n), n=0..50); # Wesley Ivan Hurt, Sep 26 2014

MATHEMATICA

Table[Sum[Sum[Binomial[k, j] Binomial[n - k - j, k] Floor[(j + 2)/2], {j, 0, n - 2 k}], {k, 0, Floor[n/2]}], {n, 0, 30}] (* Wesley Ivan Hurt, Sep 26 2014 *)

CROSSREFS

Cf. A108359.

Sequence in context: A235684 A018082 A018083 * A082423 A176485 A119266

Adjacent sequences:  A108358 A108359 A108360 * A108362 A108363 A108364

KEYWORD

easy,nonn

AUTHOR

Paul Barry, May 31 2005

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 June 15 22:06 EDT 2021. Contains 345053 sequences. (Running on oeis4.)