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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

Table of n, a(n) for n=1..7.

CROSSREFS

a(n)=A064049(n)/6 for n>1.

Sequence in context: A193500 A163885 A120338 * A162128 A337969 A234566

Adjacent sequences:  A064047 A064048 A064049 * A064051 A064052 A064053

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 May 14 19:50 EDT 2021. Contains 343902 sequences. (Running on oeis4.)