login
A013620
Triangle of coefficients in expansion of (2+3x)^n.
8
1, 2, 3, 4, 12, 9, 8, 36, 54, 27, 16, 96, 216, 216, 81, 32, 240, 720, 1080, 810, 243, 64, 576, 2160, 4320, 4860, 2916, 729, 128, 1344, 6048, 15120, 22680, 20412, 10206, 2187, 256, 3072, 16128, 48384, 90720, 108864, 81648, 34992, 6561, 512
OFFSET
0,2
COMMENTS
Row sums give A000351; central terms give A119309. - Reinhard Zumkeller, May 14 2006
FORMULA
G.f.: 1 / [1 - x(2+3y)].
T(n,k) = A007318(n,k) * A036561(n,k). - Reinhard Zumkeller, May 14 2006
EXAMPLE
Triangle begins:
1;
2,3;
4,12,9;
8,36,54,27;
16,96,216,216,81;
MATHEMATICA
Flatten[Table[Binomial[i, j] 2^(i-j) 3^j, {i, 0, 10}, {j, 0, i}]] (* Vincenzo Librandi, Apr 22 2014 *)
PROG
(Haskell)
a013620 n k = a013620_tabl !! n !! k
a013620_row n = a013620_tabl !! n
a013620_tabl = iterate (\row ->
zipWith (+) (map (* 2) (row ++ [0])) (map (* 3) ([0] ++ row))) [1]
-- Reinhard Zumkeller, May 26 2013, Apr 02 2011
CROSSREFS
KEYWORD
tabl,nonn,easy
AUTHOR
STATUS
approved