The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #8 Jun 09 2023 22:22:38
%S 4,30,1372,408599,858105364,13486744809160,1716349328902123738
%N Number of n X n 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards.
%C Diagonal of A201981.
%e Some solutions for n=3
%e ..0..3..3....0..0..2....2..3..3....0..2..2....1..2..2....0..2..3....0..1..2
%e ..0..3..3....2..3..0....3..1..2....1..0..2....3..0..2....1..0..3....2..1..1
%e ..3..2..2....3..2..0....3..3..0....3..3..0....3..2..0....2..1..0....3..2..0
%Y Cf. A201981.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 07 2011