cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A208857 Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors.

This page as a plain text file.
%I A208857 #8 Jul 22 2025 21:31:41
%S A208857 1,11,5796,44452082,4071491223248,4445765748006060562,
%T A208857 57867813487534623493632032,8978812485595759770697498996138448
%N A208857 Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors.
%C A208857 Diagonal of A208864
%e A208857 Some solutions for n=4
%e A208857 ..0..1..0..0....0..0..1..0....0..0..0..1....0..0..0..1....0..1..1..2
%e A208857 ..2..2..1..2....2..1..2..2....1..1..1..2....0..1..1..0....0..1..0..0
%e A208857 ..1..1..3..2....1..3..0..0....2..2..2..0....0..1..2..3....0..1..3..1
%e A208857 ..0..3..0..0....1..3..2..2....0..3..0..1....3..0..3..1....1..2..2..0
%K A208857 nonn
%O A208857 1,2
%A A208857 _R. H. Hardin_ Mar 02 2012

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.