OFFSET
0,5
FORMULA
Exponential Riordan array [1/sqrt(1+2x+4x^2), arctan(sqrt(3)*x/(1+x))/sqrt(3)].
EXAMPLE
Triangle begins
1,
-1, 1,
-1, -4, 1,
21, 3, -9, 1,
-111, 144, 30, -16, 1,
-345, -1599, 450, 110, -25, 1,
14895, 2844, -9549, 840, 285, -36, 1,
-143955, 208179, 62181, -36309, 735, 609, -49, 1,
-760095, -3824064, 1147068, 442176, -103194, -1344, 1148, -64, 1
MATHEMATICA
(* The function RiordanArray is defined in A256893. *)
RiordanArray[1/Sqrt[1 + 2# + 4#^2]&, ArcTan[Sqrt[3] #/(1 + #)]/Sqrt[3]&, 10, True] // Flatten (* Jean-François Alcover, Jul 19 2019 *)
CROSSREFS
KEYWORD
AUTHOR
Paul Barry, Dec 05 2010
STATUS
approved