

A117179


Riordan array ((1x^2)/(1+x^2)^2,x/(1+x^2)).


2



1, 0, 1, 3, 0, 1, 0, 4, 0, 1, 5, 0, 5, 0, 1, 0, 9, 0, 6, 0, 1, 7, 0, 14, 0, 7, 0, 1, 0, 16, 0, 20, 0, 8, 0, 1, 9, 0, 30, 0, 27, 0, 9, 0, 1, 0, 25, 0, 50, 0, 35, 0, 10, 0, 1, 11, 0, 55, 0, 77, 0, 44, 0, 11, 0, 1
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,4


COMMENTS

Inverse is A117178. Row sums are (1)^n*A098554(n+1). Diagonal sums are 1,0,2,0,2,0,2,... with g.f. (1x^2)/(1+x^2).
Apparently, with the rows deaerated and then reversed, this matrix becomes signed A034807 with the twos on the diagonal removed. Apparently, D(2n,k+1) = D(2(n1),k+1) + D(2n,k) where D(n,k) is the kth element on the nth diagonal.  Tom Copeland, May 30 2017


LINKS

Table of n, a(n) for n=0..65.


EXAMPLE

Triangle begins
1,
0, 1,
3, 0, 1,
0, 4, 0, 1,
5, 0, 5, 0, 1,
0, 9, 0, 6, 0, 1,
7, 0, 14, 0, 7, 0, 1,
0, 16, 0, 20, 0, 8, 0, 1


CROSSREFS

Sequence in context: A108197 A318455 A049769 * A111526 A117178 A111527
Adjacent sequences: A117176 A117177 A117178 * A117180 A117181 A117182


KEYWORD

easy,sign,tabl


AUTHOR

Paul Barry, Mar 01 2006


STATUS

approved



