A138779 - OEIS

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A138779

Triangle read by rows: T(n,k)=k*binomial(n-2k,3k+1) (n>=6, 0<=k<=(n-1)/5).

1, 5, 15, 35, 70, 126, 2, 210, 16, 330, 72, 495, 240, 715, 660, 1001, 1584, 3, 1365, 3432, 33, 1820, 6864, 198, 2380, 12870, 858, 3060, 22880, 3003, 3876, 38896, 9009, 4, 4845, 63648, 24024, 56, 5985, 100776, 58344, 420

(list; graph; refs; listen; history; text; internal format)

OFFSET

6,2

COMMENTS

Row n contains floor((n-1)/5) terms.

Row sums yield A137360.

REFERENCES

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

LINKS

Table of n, a(n) for n=6..47.

MAPLE

T:=proc(n, k) options operator, arrow: k*binomial(n-2*k, 3*k+1) end proc: for n from 6 to 23 do seq(T(n, k), k=1..(n-1)*1/5) end do; # yields sequence in triangular form

MATHEMATICA

Select[Flatten[Table[k*Binomial[n-2k, 3k+1], {n, 6, 30}, {k, 0, (n-1)/5}]], #>0&] (* Harvey P. Dale, May 24 2015 *)

CROSSREFS

Cf. A137360.

Sequence in context: A289389 A008487 A000743 * A341184 A090580 A000332

Adjacent sequences: A138776 A138777 A138778 * A138780 A138781 A138782

KEYWORD

nonn,tabf

AUTHOR

Emeric Deutsch, May 10 2008

STATUS

approved