OFFSET
0,4
COMMENTS
The Riordan array ( (1-x-sqrt(1-2x-3x^2-4x^3))/(2x^2(1+x)), (1-x-sqrt(1-2x-3x^2-4x^3))/(2x(1+x)) read downwards antidiagonals. - R. J. Mathar, Oct 31 2011
LINKS
D. Merlini, D. G. Rogers, R. Sprugnoli and M. C. Verri, On some alternative characterizations of Riordan arrays, Canad J. Math., 49 (1997), 301-320.
EXAMPLE
1;
1;
1,2;
2,5;
1,5,12;
3,14,31;
1,9,38,83;
4,28,106,227;
1,14,84,301,634;
5,48,252,864,1799;
1,20,157,758,2508,5171;
6,75,504,2283,7348,15027;
1,27,265,1602,6897,21699,44074;
MAPLE
read("transforms3") ;
A071950 := proc(d, c)
local g, h, n, k ;
n := (d + (d mod 2))/2+c ;
k := (d-(d mod 2))/2-c ;
g := (1-x-sqrt(1-2*x-3*x^2-4*x^3))/2/x^2/(1+x) ;
h := (1-x-sqrt(1-2*x-3*x^2-4*x^3))/2/x/(1+x) ;
RIORDAN(g, h, n, k) ;
end proc:
for n from 0 to 12 do
for k from 0 to floor(n/2) do
printf("%d, ", A071950(n, k)) ;
end do:
printf("\n") ;
end do; # R. J. Mathar, Oct 31 2011
CROSSREFS
KEYWORD
nonn,easy,tabf
AUTHOR
N. J. A. Sloane, Jun 15 2002
STATUS
approved