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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: A334374 A103448 A186904 * A078803 A368227 A368179 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 May 18 15:50 EDT 2024. Contains 372664 sequences. (Running on oeis4.)