A218351 - OEIS

%I #12 Jul 18 2026 12:36:53

%S 17,547,14811,401253,10982565,300126903,8199377227,224032447213,

%T 6121258910011,167250519310183,4569773233045519,124859601874166153,

%U 3411530022687206815,93212992000176142919,2546851962811003392065,69587455310149651602261,1901333099020390131490059,51949989227881197782609163

%N Number of n X 5 binary arrays with every 0 a horizontal or vertical neighbor to some 1.

%H R. H. Hardin, <a href="/A218351/b218351.txt">Table of n, a(n) for n = 1..51</a>

%e Some solutions for n=3:

%e ..1..0..0..1..0....1..1..0..0..1....1..1..0..1..0....1..0..0..1..0

%e ..0..0..0..1..0....1..1..1..0..1....0..1..1..1..1....0..1..1..1..1

%e ..1..1..0..0..1....0..0..1..1..1....0..1..0..0..1....1..1..1..0..1

%Y Column 5 of A218354.

%K nonn,changed

%O 1,1

%A _R. H. Hardin_, Oct 26 2012

%E New name from _Andrew Howroyd_, Jul 18 2026