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

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A027378 Expansion of (1+x^2-x^3)/(1-x)^4. 0

%I

%S 1,4,11,23,41,66,99,141,193,256,331,419,521,638,771,921,1089,1276,

%T 1483,1711,1961,2234,2531,2853,3201,3576,3979,4411,4873,5366,5891,

%U 6449,7041,7668,8331,9031,9769,10546

%N Expansion of (1+x^2-x^3)/(1-x)^4.

%C If Y is a 3-subset of an n-set X then, for n>=4, a(n-4) is the number of (n-3)-subsets of X which have no exactly one element in common with Y. - _Milan Janjic_, Dec 28 2007

%F a(n-3)=binomial(n,3)-3*n+9, n=4,5,6,.... - _Milan Janjic_, Dec 28 2007

%K nonn

%O 0,2

%A _N. J. A. Sloane_.

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 April 20 19:58 EDT 2014. Contains 240821 sequences.