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, 230643876376, 8267423666602776, 2588783179055230532664, 7821803477915366921777312696, 249798463487076698389715808536913464, 91691177557134991595405594421320691579192632, 417955522215118460342460602239817237893422169776951160

Offset

1,3

Links

Max Alekseyev, Table of n, a(n) for n = 1..18

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

nonn,changed

Author

Floor van Lamoen, Aug 24 2001

Extensions

a(7) from Lars Blomberg, Apr 11 2012

Terms a(8) onward from Max Alekseyev, Jul 20 2024

Status

approved