OFFSET
0,6
COMMENTS
Triangle T(n,k), 0 <= k <= n, read by rows, given by [0, 1, -1, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 1, -1, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938.
Maximal column entries: A038149 = {1, 1, 2, 5, 10, 22, ...}.
Triangle read by rows: T(n,n-k) is the number of ways to tile a 2 X n rectangle with k pieces of 2 X 2 tiles and n-2k pieces of 1 X 2 tiles (0 <= k <= floor(n/2)). - Philippe Deléham, Feb 17 2014
Diagonal sums are A013979(n). - Philippe Deléham, Feb 17 2014
T(n,k) is the number of ways to tile a 2 X n rectangle with k pieces of 2 X 2 tiles and 1 X 2 tiles. - Emeric Deutsch, Aug 14 2014
LINKS
FORMULA
T(0, 0) = 1, T(n, k) = 0 for k < 0 or for n < k, T(n, k) = T(n-1, k-1) + T(n-2, k-1) + T(n-2, k-2).
G.f.: 1/(1-yx(1-x)-x^2*y^2). - Paul Barry, Oct 04 2005
EXAMPLE
Triangle begins:
1;
0, 1;
0, 1, 2;
0, 0, 2, 3;
0, 0, 1, 5, 5;
0, 0, 0, 3, 10, 8;
0, 0, 0, 1, 9, 20, 13;
0, 0, 0, 0, 4, 22, 38, 21;
0, 0, 0, 0, 1, 14, 51, 71, 34;
0, 0, 0, 0, 0, 5, 40, 111, 130, 55;
0, 0, 0, 0, 0, 1, 20, 105, 233, 235, 89;
0, 0, 0, 0, 0, 0, 6, 65, 256, 474, 420, 144;
PROG
(Haskell)
a111006 n k = a111006_tabl !! n !! k
a111006_row n = a111006_tabl !! n
a111006_tabl = map fst $ iterate (\(us, vs) ->
(vs, zipWith (+) (zipWith (+) ([0] ++ us ++ [0]) ([0, 0] ++ us))
([0] ++ vs))) ([1], [0, 1])
-- Reinhard Zumkeller, Aug 15 2013
CROSSREFS
KEYWORD
AUTHOR
Philippe Deléham, Oct 02 2005
STATUS
approved