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A138775 Triangle read by rows: T(n,k)=binomial(n-2k,3k) (n>=0, 0<=k<=n/5). 0
1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 10, 1, 20, 1, 35, 1, 56, 1, 1, 84, 7, 1, 120, 28, 1, 165, 84, 1, 220, 210, 1, 286, 462, 1, 1, 364, 924, 10, 1, 455, 1716, 55, 1, 560, 3003, 220, 1, 680, 5005, 715, 1, 816, 8008, 2002, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

COMMENTS

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

Row sums yield A137356.

REFERENCES

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

LINKS

Table of n, a(n) for n=0..54.

MAPLE

T:=proc(n, k) options operator, arrow: binomial(n-2*k, 3*k) end proc: for n from 0 to 20 do seq(T(n, k), k=0..(1/5)*n) end do; # yields sequence in triangular form

MATHEMATICA

Flatten[Table[Binomial[n-2k, 3k], {n, 0, 20}, {k, 0, Floor[n/5]}]] (* Harvey P. Dale, Oct 14 2012 *)

CROSSREFS

Cf. A137356.

Sequence in context: A185088 A064947 A059926 * A209385 A121529 A006370

Adjacent sequences:  A138772 A138773 A138774 * A138776 A138777 A138778

KEYWORD

nonn,tabf

AUTHOR

Emeric Deutsch, May 10 2008

STATUS

approved

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Last modified September 25 19:48 EDT 2017. Contains 292500 sequences.