OFFSET
1,2
LINKS
Anthony J. Guttmann and Iwan Jensen, Table of n, a(n) for n = 1..17
Anthony J. Guttmann and Iwan Jensen, The gerrymander sequence, or A348456, arXiv:2211.14482 [math.CO], 2022.
FORMULA
a(2*n)/2 = A348456(n).
EXAMPLE
For n = 2, the square can be split vertically or horizontally, and then there are two ways to order the regions, so a(2) = 2*2 = 4.
For n = 3 we must choose a connected region of area 4 with a connected complement of area 5.
The possibilities are
XXO XXX XXX
XXO XOO OXO
OOO OOO OOO
4 ways 8 ways 4 ways
so a(3) = 16.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 25 2022
STATUS
approved