cp's OEIS Frontend

A064049 Number of possible arrangements of numbers 1 to n*(n+1)/2 in a triangle of n rows so that each row and each diagonal is increasing or decreasing.

%I A064049 #17 Jul 20 2024 14:39:34
%S A064049 1,6,24,180,4212,461064,302693712,1383863258256,49604541999616656,
%T A064049 15532699074331383195984,46930820867492201530663876176,
%U A064049 1498790780922460190338294851221480784,550147065342809949572433566527924149475155792,2507733133290710762054763613438903427360533018661706960
%N A064049 Number of possible arrangements of numbers 1 to n*(n+1)/2 in a triangle of n rows so that each row and each diagonal is increasing or decreasing.
%H A064049 Max Alekseyev, <a href="/A064049/b064049.txt">Table of n, a(n) for n = 1..18</a>
%e A064049 The following triangle of 4 rows satisfies the requirements:
%e A064049 ....1
%e A064049 ...3 2
%e A064049 ..4 5 8
%e A064049 .6 7 9 10
%Y A064049 a(n)=6*A064050(n) for n>1.
%K A064049 nonn
%O A064049 1,2
%A A064049 _Floor van Lamoen_, Aug 24 2001
%E A064049 a(7) from _Lars Blomberg_, Apr 11 2012
%E A064049 Terms a(8) onward from _Max Alekseyev_, Jul 20 2024