This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A117179 Riordan array ((1-x^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. (1-x^2)/(1+x^2). Apparently, with the rows de-aerated and then reversed, this matrix becomes signed A034807 with the twos on the diagonal removed. Apparently, |D(2n,k+1)| = |D(2(n-1),k+1)| + |D(2n,k)| where D(n,k) is the k-th element on the n-th diagonal. - Tom Copeland, May 30 2017 LINKS 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 16 21:37 EST 2019. Contains 319206 sequences. (Running on oeis4.)