login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 A234566 A201974

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 16 09:06 EST 2019. Contains 330020 sequences. (Running on oeis4.)