A138777 - OEIS

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A138777

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

1, 3, 6, 10, 15, 21, 1, 28, 6, 36, 21, 45, 56, 55, 126, 66, 252, 1, 78, 462, 9, 91, 792, 45, 105, 1287, 165, 120, 2002, 495, 136, 3003, 1287, 1, 153, 4368, 3003, 12, 171, 6188, 6435, 78, 190, 8568, 12870, 364

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

OFFSET

2,2

COMMENTS

Row n contains floor((n+3)/5) terms.

Row sums yield A137358.

REFERENCES

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

LINKS

Table of n, a(n) for n=2..47.

MAPLE

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

MATHEMATICA

Flatten[Table[Binomial[n-2k, 3k+2], {n, 2, 20}, {k, 0, (n-2)/5}]] (* Harvey P. Dale, Mar 07 2013 *)

CROSSREFS

Cf. A137358.

Sequence in context: A037452 A047800 A109443 * A096895 A034175 A361670

Adjacent sequences: A138774 A138775 A138776 * A138778 A138779 A138780

KEYWORD

nonn,tabf

AUTHOR

Emeric Deutsch, May 10 2008

STATUS

approved

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