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A064049 Number of possible arrangements of numbers 1 to n*(n+1)/2 in a triangle of n rows so that each row and each diagonal is increasing or decreasing. 2
1, 6, 24, 180, 4212, 461064, 302693712 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
The following triangle of 4 rows satisfies the requirements:
....1
...3 2
..4 5 8
.6 7 9 10
CROSSREFS
a(n)=6*A064050(n) for n>1.
Sequence in context: A200904 A293488 A038033 * A336267 A018981 A052594
KEYWORD
more,nonn
AUTHOR
Floor van Lamoen, Aug 24 2001
EXTENSIONS
a(7) from Lars Blomberg, Apr 11 2012
STATUS
approved

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Last modified March 4 15:24 EST 2024. Contains 370532 sequences. (Running on oeis4.)