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A138778 Triangle read by rows: T(n,k)=k*binomial(n-2k,3k) (n>=5, 1<=k<=n/5). 0


%S 1,4,10,20,35,56,2,84,14,120,56,165,168,220,420,286,924,3,364,1848,30,

%T 455,3432,165,560,6006,660,680,10010,2145,816,16016,6006,4,969,24752,

%U 15015,52,1140,37128,34320,364

%N Triangle read by rows: T(n,k)=k*binomial(n-2k,3k) (n>=5, 1<=k<=n/5).

%C Row n contains floor(n/5) terms.

%C Row sums yield A137359.

%D D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.4.

%p T:=proc(n,k) options operator, arrow: k*binomial(n-2*k,3*k) end proc: for n from 5 to 22 do seq(T(n,k),k=1..(1/5)*n) end do; # yields sequence in triangular form

%t Flatten[Table[k*Binomial[n-2k,3k],{n,5,30},{k,1,n/5}]] (* _Harvey P. Dale_, Dec 20 2014 *)

%Y Cf. A137359.

%K nonn,tabf

%O 5,2

%A _Emeric Deutsch_, May 10 2008

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Last modified August 4 18:15 EDT 2021. Contains 346455 sequences. (Running on oeis4.)