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 A138780 Triangle read by rows: T(n,k)=k*binomial(n-2k,3k+2) (n>=7, 1<=k<=(n-2)/5). 0

%I

%S 1,6,21,56,126,252,2,462,18,792,90,1287,330,2002,990,3003,2574,3,4368,

%T 6006,36,6188,12870,234,8568,25740,1092,11628,48620,4095,15504,87516,

%U 13104,4,20349,151164,37128,60

%N Triangle read by rows: T(n,k)=k*binomial(n-2k,3k+2) (n>=7, 1<=k<=(n-2)/5).

%C Row n contains floor((n-2)/5) terms.

%C Row sums yield A137361.

%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+2) end proc: for n from 7 to 23 do seq(T(n,k),k=1..(n-2)*1/5) end do; # yields sequence in triangular form

%t Flatten[Table[k*Binomial[n-2k,3k+2],{n,7,30},{k,1,(n-2)/5}]] (* _Harvey P. Dale_, Aug 22 2015 *)

%Y Cf. A137361.

%K nonn,tabf

%O 7,2

%A _Emeric Deutsch_, May 10 2008

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Last modified September 20 00:28 EDT 2021. Contains 347577 sequences. (Running on oeis4.)