login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A166887
Column 3 of triangle
A166884
.
3
1, 3, 18, 157, 1812, 25989, 445255, 8865333, 201058614, 5114874693, 144207579708, 4462151144553, 150316762118466, 5475746846833734, 214463847533104125, 8986421286160678944, 401112805593137715609, 18999650382886046745879
(
list
;
graph
;
refs
;
listen
;
history
;
text
;
internal format
)
OFFSET
1,2
COMMENTS
Triangle
A166884
transforms diagonals in the triangle
A166880
of coefficients in the successive iterations of x+x^2+x^3.
LINKS
Table of n, a(n) for n=1..18.
PROG
(PARI) {a(n)=local(F=x, M, N, P, m=n+2); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x+x^2+x^3+x*O(x^(m+2)))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, M[r, c]); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+3, 3]}
CROSSREFS
Cf.
A166880
,
A166884
,
A166885
,
A166886
.
Sequence in context:
A246529
A305824
A116956
*
A075678
A341331
A089901
Adjacent sequences:
A166884
A166885
A166886
*
A166888
A166889
A166890
KEYWORD
nonn
AUTHOR
Paul D. Hanna
, Nov 21 2009
STATUS
approved
Lookup
|
Welcome
|
Wiki
|
Register
|
Music
|
Plot 2
|
Demos
|
Index
|
Browse
|
WebCam
Contribute new seq. or comment
|
Format
|
Style Sheet
|
Transforms
|
Superseeker
|
Recents
The OEIS Community
| Maintained by
The OEIS Foundation Inc.
License Agreements, Terms of Use, Privacy Policy.
.
Last modified September 19 18:51 EDT 2024. Contains 376014 sequences. (Running on oeis4.)