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.

1, 1, 4, 30, 702, 76844, 50448952

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