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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
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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
A368627
Adjacent sequences:
A105618
A105619
A105620
*
A105622
A105623
A105624
KEYWORD
sign
AUTHOR
Paul D. Hanna
, Apr 16 2005
STATUS
approved
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Last modified June 8 05:45 EDT 2024. Contains 373207 sequences. (Running on oeis4.)