OFFSET
0,4
COMMENTS
LINKS
EXAMPLE
Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
0;
1;
1,3;
1,3,5,7;
1,3,5,7,5,11,17,15;
1,3,5,7,5,11,17,15,5,11,17,23,29,35,41,31;
1,3,5,7,5,11,17,15,5,11,17,23,29,35,41,31,5,11,17,23,29,35,41,47,53,59,65,71,77,83,89,63;
...
Right border gives A000225.
Apart from the initial 0 the row sums give A000302.
Rows converge to A256258.
.
Illustration of initial terms in the fourth quadrant of the square grid:
---------------------------------------------------------------------------
n a(n) Compact diagram
---------------------------------------------------------------------------
0 0 _
1 1 |_|_ _
2 1 |_| |
3 3 |_ _|_ _ _ _
4 1 |_| | | |
5 3 |_ _| | |
6 5 |_ _ _| |
7 7 |_ _ _ _|_ _ _ _ _ _ _ _
8 1 |_| | | |_ _ | |
9 3 |_ _| | |_ | | |
10 5 |_ _ _| | | | | |
11 7 |_ _ _ _| | | | |
12 5 | | |_ _ _| | | |
13 11 | |_ _ _ _ _| | |
14 17 |_ _ _ _ _ _ _| |
15 15 |_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
16 1 |_| | | |_ _ | |_ _ _ _ _ _ | |
17 3 |_ _| | |_ | | |_ _ _ _ _ | | |
18 5 |_ _ _| | | | | |_ _ _ _ | | | |
19 7 |_ _ _ _| | | | |_ _ _ | | | | |
20 5 | | |_ _ _| | | |_ _ | | | | | |
21 11 | |_ _ _ _ _| | |_ | | | | | | |
22 17 |_ _ _ _ _ _ _| | | | | | | | | |
23 15 |_ _ _ _ _ _ _ _| | | | | | | | |
24 5 | | | | | | |_ _ _| | | | | | | |
25 11 | | | | | |_ _ _ _ _| | | | | | |
26 17 | | | | |_ _ _ _ _ _ _| | | | | |
27 23 | | | |_ _ _ _ _ _ _ _ _| | | | |
28 29 | | |_ _ _ _ _ _ _ _ _ _ _| | | |
29 35 | |_ _ _ _ _ _ _ _ _ _ _ _ _| | |
30 41 |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _| |
31 31 |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|
.
a(n) is also the number of cells in the n-th region of the diagram.
A256264(n) gives the total number of cells after n-th stage.
MATHEMATICA
Flatten@Join[{0}, NestList[Join[#, Range[Length[#] - 1]*6 - 1, {2 #[[-1]] + 1}] &, {1}, 6]] (* Ivan Neretin, Feb 14 2017 *)
CROSSREFS
KEYWORD
AUTHOR
Omar E. Pol, Mar 30 2015
EXTENSIONS
Terms a(95) to a(98) fixed by Ivan Neretin, Feb 14 2017
STATUS
approved