|
Search: id:A142717
|
|
|
| A142717 |
|
First (leftmost) odd term in the n'th row of triangle A120070. |
|
+0
3
|
|
| 3, 5, 15, 21, 35, 45, 63, 77, 99, 117, 143, 165, 195, 221, 255, 285, 323, 357, 399, 437, 483, 525, 575, 621, 675, 725, 783, 837, 899, 957, 1023, 1085, 1155, 1221, 1295, 1365, 1443, 1517, 1599, 1677, 1763, 1845, 1935, 2021, 2115, 2205, 2303, 2397, 2499, 2597
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Also: Records sequence of A100181.
The last (rightmost) term in the n'th row of triangle A120070 is A005408(n).
|
|
FORMULA
|
First differences: a(n+1)-a(n)=A142954(n).
a(n)=(n+1)^2-1 =A000466((n+1)/2) if n odd. a(n)= (n+1)^2-4 =A078371(n/2-1) if n even. a(n) = 2*a(n-1) -2*a(n-3) +a(n-4). G.f.: x(3-x+5x^2-3x^3)/((1+x)(1-x)^3). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2008
|
|
EXAMPLE
|
The odd terms of A120070 build the irregular triangle
3;
5;
15,7;
21,9;
35,27,11;
45,33,13;
63,55,39,15;
The leftmost column defines this sequence.
|
|
CROSSREFS
|
Sequence in context: A165260 A059528 A070079 this_sequence A057742 A101129 A128396
Adjacent sequences: A142714 A142715 A142716 this_sequence A142718 A142719 A142720
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Paul Curtz (bpcrtz(AT)free.fr), Sep 26 2008
|
|
EXTENSIONS
|
Edited and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2008
|
|
|
Search completed in 0.002 seconds
|
