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

Author

Floor van Lamoen, Aug 24 2001

Keywords

• nonn

Links

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

Crossrefs

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

Extensions

a(7) from Lars Blomberg, Apr 11 2012

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