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A064050 Number of essentially different (not mappable to each other by reflection or rotation) arrangements of numbers 1 to n*(n+1)/2 in a triangle of n rows, in such a way that each row and each diagonal is increasing or decreasing. 2
1, 1, 4, 30, 702, 76844, 50448952 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
CROSSREFS
a(n)=A064049(n)/6 for n>1.
Sequence in context: A193500 A163885 A120338 * A162128 A337969 A234566
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 13:15 EST 2024. Contains 370532 sequences. (Running on oeis4.)