OFFSET
0,4
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1325 (rows 0..50)
He, Tian-Xiao. "A-sequences, Z-sequence, and B-sequences of Riordan matrices." Discrete Mathematics 343.3 (2020): 111718. Also arXiv:1909.02639.
EXAMPLE
Triangle begins:
1;
1, 1;
2, 2, 1;
4, 4, 3, 1;
8, 9, 7, 4, 1;
17, 20, 17, 11, 5, 1;
37, 45, 41, 29, 16, 6, 1;
...
PROG
(PARI) \\ ColGf gives the g.f. of the k-th column.
ColGf(k, n)={my(g=(1 - x + x^2 - sqrt(1 - 2*x - x^2 - 2*x^3 + x^4 + O(x^(n-k+4))))/(2*x^2)); (g - 1)/x*(x*g)^k}
T(n, k) = {polcoef(ColGf(k, n), n)} \\ Andrew Howroyd, Mar 02 2023
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Mar 06 2020
EXTENSIONS
Terms a(28) and beyond from Andrew Howroyd, Mar 02 2023
STATUS
approved