A280904 Number of 3Xn 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 9, 646, 22568, 492490, 9426050, 162640161, 2636238543, 40818734359, 610807332682, 8899797476985, 126936297853576, 1779063560531884, 24572630681534366, 335222285940398228, 4524762545977409290

Offset

1,2

Comments

Row 3 of A280902.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 33*a(n-1) -294*a(n-2) -667*a(n-3) +16806*a(n-4) -5121*a(n-5) -389950*a(n-6) +278709*a(n-7) +5095965*a(n-8) -3346390*a(n-9) -41873331*a(n-10) +15827649*a(n-11) +225089912*a(n-12) +21687735*a(n-13) -781184967*a(n-14) -677069112*a(n-15) +1532218374*a(n-16) +3816125286*a(n-17) -205248782*a(n-18) -10810606968*a(n-19) -8772390618*a(n-20) +14265527040*a(n-21) +28972645413*a(n-22) +4449696537*a(n-23) -47676340890*a(n-24) -49006792749*a(n-25) +33750291246*a(n-26) +84325212377*a(n-27) +22629768081*a(n-28) -73666126236*a(n-29) -77116545584*a(n-30) +28481649930*a(n-31) +84486500724*a(n-32) +8922526848*a(n-33) -53642734755*a(n-34) -20170947015*a(n-35) +20632416015*a(n-36) +15610729314*a(n-37) -3175177428*a(n-38) -8006609696*a(n-39) -1561010208*a(n-40) +2779299648*a(n-41) +1314081664*a(n-42) -535991040*a(n-43) -521884416*a(n-44) -26788352*a(n-45) +145327104*a(n-46) +56180736*a(n-47) -25534464*a(n-48) -17252352*a(n-49) +688128*a(n-50) +2818048*a(n-51) +983040*a(n-52) -393216*a(n-53) -262144*a(n-54) for n>60

Example

Some solutions for n=4
..0..1..1..1. .0..0..1..2. .0..1..1..0. .0..0..1..1. .0..1..0..0
..0..1..2..0. .2..2..2..0. .0..0..1..0. .1..0..0..1. .1..0..1..0
..1..0..1..1. .0..1..2..0. .0..1..1..2. .1..0..1..1. .1..2..0..0

Crossrefs

Cf. A280902.

Sequence in context: A188394 A157597 A211611 * A210053 A128795 A323425

Adjacent sequences: A280901 A280902 A280903 * A280905 A280906 A280907

Keyword

nonn

Author

R. H. Hardin, Jan 10 2017

Status

approved