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A216216 Square array T, read by antidiagonals: T(n,k) = 0 if n-k>=3 or if k-n>=3, T(2,0) = T(1,0) = T(0,0) = T(0,1) = T(0,2) = 1, T(n,k) = T(n-1,k) + T(n,k-1). 11
1, 1, 1, 1, 2, 1, 0, 3, 3, 0, 0, 3, 6, 3, 0, 0, 0, 9, 9, 0, 0, 0, 0, 9, 18, 9, 0, 0, 0, 0, 0, 27, 27, 0, 0, 0, 0, 0, 0, 27, 54, 27, 0, 0, 0, 0, 0, 0, 0, 81, 81, 0, 0, 0, 0, 0, 0, 0, 0, 81, 162, 81, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..65.

FORMULA

T(n,n) = A025192(n).

T(n+1,n) = T(n+2,n) = T(n,n+1) = T(n,n+2) = 3^n = A000244(n).

Sum_{k, 0<=k<=n} T(n-k,k) = A068911(n).

EXAMPLE

Square array begins:

1, 1, 1,  0,  0,   0,   0,   0, 0, ... n = 0

1, 2, 3,  3,  0,   0,   0,   0, 0, ... n = 1

1, 3, 6,  9,  9,   0,   0,   0, 0, ... n = 2

0, 3, 9, 18, 27,  27,   0,   0, 0, ... n = 3

0, 0, 9, 27, 54,  81,  81,   0, 0, ... n = 4

0, 0, 0, 27, 81, 162, 243, 243, 0, ... n = 5

....

CROSSREFS

Cf. A000244, A025192, A068911, A068913

Sequence in context: A103432 A103448 A186904 * A078803 A130403 A130402

Adjacent sequences:  A216213 A216214 A216215 * A216217 A216218 A216219

KEYWORD

nonn,tabl

AUTHOR

Philippe Deléham, Mar 13 2013

STATUS

approved

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Last modified April 25 21:06 EDT 2019. Contains 322461 sequences. (Running on oeis4.)