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A027378 Expansion of (1+x^2-x^3)/(1-x)^4. 0


%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

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).

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

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_.

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Last modified May 27 19:04 EDT 2017. Contains 287207 sequences.