login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A105621 Column 2 of triangle A105620. 1
1, -3, -7, -39, -315, -3243, -40167, -579159, -9514395, -175345083, -3582404487, -80368306119, -1964266364475, -51955106653323, -1478719724319207, -45062796853058679, -1463985729352297755, -50509695778598958363, -1844377821680825976327 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A105620 is the matrix inverse square-root of triangle A105615.

LINKS

Table of n, a(n) for n=0..18.

PROG

(PARI) {a(n)=local(R, M=matrix(n+3, n+3, m, j, if(m>=j, if(m==j, 1, if(m==j+1, -2*j, polcoeff(1/sum(i=0, m-j, (2*i)!/i!/2^i*x^i)+O(x^m), m-j)))))); R=(M+M^0)/2; for(i=1, floor(2*log(n+2)), R=(R+M*R^(-1))/2); return(if(n<0, 0, R[n+3, 3]))}

CROSSREFS

Cf. A105615, A105620.

Sequence in context: A209326 A307952 A074582 * A181081 A166895 A018998

Adjacent sequences:  A105618 A105619 A105620 * A105622 A105623 A105624

KEYWORD

sign

AUTHOR

Paul D. Hanna, Apr 16 2005

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 13:56 EST 2022. Contains 350466 sequences. (Running on oeis4.)