|
Search: id:A124072
|
|
| |
|
| 0, 1, 0, 2, 1, 3, 1, 4, 2, 5, 2, 6, 3, 7, 3, 8, 4, 9, 4, 10, 5, 11, 5, 12, 6, 13, 6, 14, 7, 15, 7, 16, 8, 17, 8, 18, 9, 19, 9, 20, 10, 21, 10, 22, 11, 23, 11, 24, 12, 25, 12, 26
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
COMMENT
|
A129819 and its repeated differences are
0.0.1..1..3..4..7...8..12..14.19..21.27....
..0.1..0..2..1..3...1...4...2..5...2..6....
....1.-1..2.-1..2..-2...3..-2..3..-3..4....
......-2..3.-3..3..-4...5..-5..5..-6..7....
..........5.-6..6..-7...9.-10.10.-11.13...
...........-11.12.-13..16.-19.20.-21.24.-27
...............23.-25..29.-35.39.-41.45.-51
The left edge is A130668.
I discovered the array 1 1 -2 1 -3 2 in studying the singular points of planar polynomial differential systems (inspired by the reference). Hence this "natural" array. Filling zeros back in, we associate it with a "theoretical" array: 0, 0 -1, 0 -2 1, 0 -3 1 -2, .
|
|
REFERENCES
|
P. Curtz, Stabilite locale des systemes quadratiques. Ann. sc. Ecole Norm. Sup.,1980, pp 293-302.
|
|
LINKS
|
Paul Curtz, Stabilite locale des systemes quadratiques, Ann. sc. Ecole Norm. Sup. vol 13 no 3 (1980) pp 293-302.
|
|
FORMULA
|
a(2n)=A004526(n). a(2n+1)=A000027(n+1) .
G.f.: x*(1+x^2+x^3)/((x^2+1)*(x-1)^2*(1+x)^2). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 25 2009]
|
|
CROSSREFS
|
Sequence in context: A143862 A115118 A115121 this_sequence A100053 A029194 A059499
Adjacent sequences: A124069 A124070 A124071 this_sequence A124073 A124074 A124075
|
|
KEYWORD
|
nonn,uned
|
|
AUTHOR
|
Paul Curtz (bpcrtz(AT)free.fr), Jun 26 2007
|
|
EXTENSIONS
|
Partially edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 07 2008
|
|
|
Search completed in 0.005 seconds
|
