A064049 - OEIS

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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.

1, 6, 24, 180, 4212, 461064, 302693712 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,2`
	LINKS	`Table of n, a(n) for n=1..7.`
	EXAMPLE	`The following triangle of 4 rows satisfies the requirements:` `....1` `...3 2` `..4 5 8` `.6 7 9 10`
	CROSSREFS	`a(n)=6A064050(n) for n>1.` `Sequence in context: A200904 A293488 A038033 A336267 A018981 A052594` `Adjacent sequences: A064046 A064047 A064048 * A064050 A064051 A064052`
	KEYWORD	`more,nonn`
	AUTHOR	`Floor van Lamoen, Aug 24 2001`
	EXTENSIONS	`a(7) from Lars Blomberg, Apr 11 2012`
	STATUS	`approved`

Last modified March 7 17:11 EST 2021. Contains 341897 sequences. (Running on oeis4.)