OFFSET
0,2
FORMULA
G.f.: ((1 - 4*x*y)*sin(arcsin((216*x^2) / (1 - 4*x*y)^3 - 1)/3))/(6*x) + (1 - 4*x*y) / (12*x).
EXAMPLE
Triangle T(n, m) begins:
[0] 1;
[1] 2, 2;
[2] 10, 16, 6;
[3] 64, 140, 96, 20;
[4] 462, 1280, 1260, 512, 70;
[5] 3584, 12012, 15360, 9240, 2560, 252;
[6] 29172, 114688, 180180, 143360, 60060, 12288, 924;
MAPLE
T := (n, k) -> ifelse(n mod 2 = 1, 4^n*((3*n - k - 1)/2)! / (k!*(n + 1 - k)! * ((n - k - 1)/2)!), binomial(n + 1, k) * ((n - k)/2)! * (3*n - k)! / (((3*n - k)/2)! * (n + 1)! * (n - k)!)): for n from 0 to 6 do seq(simplify(T(n, k)), k=0..n) od;
# Alternative:
gf := ((1 - 4*x*y)*sin(arcsin((216*x^2) / (1 - 4*x*y)^3 - 1)/3))/(6*x) + (1 - 4*x*y) / (12*x): assume(x > 0); serx := series(gf, x, 9): poly := n -> simplify(coeff(serx, x, n)): seq(print(seq(coeff(poly(n), y, k), k = 0..n)), n = 0..6); # Peter Luschny, Feb 15 2023
PROG
(Maxima)
T(n, m):=if n<m then 0 else 1/(n+1)*binomial(n+1, m)*if evenp(n-m+1) then 4^(n)*binomial((3*n-m+1)/2-1, n) else binomial((3*n-m)/2, n)*binomial(3*n-m, (3*n-m)/2)/binomial(n-m, (n-m)/2);
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Vladimir Kruchinin, Feb 14 2023
STATUS
approved