|
|
A020906
|
|
Triangle where n-th row is the first n terms of the sequence in reverse order, starting with a(1) = 1 and a(2) = 2.
|
|
2
|
|
|
1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Lim f(f(...f(n))) where f(n) is fractal sequence in A004736.
|
|
LINKS
|
|
|
EXAMPLE
|
The triangle starts:
1
2 1
1 2 1
1 1 2 1
2 1 1 2 1
1 2 1 1 2 1
Since the sequence starts 1,2,1,1,2, row 5 is the reversal of that, 2,1,1,2,1.
|
|
PROG
|
(PARI) at(n)=local(r, k); r=vector(n*(n+1)\2); r[1]=r[3]=1; r[2]=2; k=4; for(i=3, n, for(j=1, i, r[k]=r[i-j+1]; k++)); r /* Generates first n>1 rows of triangle. - Franklin T. Adams-Watters, Aug 08 2011. */
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|