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 A068416 Number of partitionings of n X n checkerboard into two edgewise-connected sets. 2
 0, 6, 53, 627, 16213, 1123743, 221984391, 127561384993, 215767063451331, 1082828220389781579, 16209089366362071416785, 726438398002211876667379681, 97741115155002465272674416929195, 39565596445488219947994403962984729307 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS One of the partitions may completely surround the other. (Cf. A271802) - Andrew Howroyd, Apr 14 2016 LINKS Benjamin Fifield, Kosuke Imai, Jun Kawahara, Christopher T. Kenny, The Essential Role of Empirical Validation in Legislative Redistricting Simulation, Tech. rep., Department of Government and Department of Statistics, Harvard University (2019). FORMULA a(n) = A271802(n) + A140517(n-2). - Andrew Howroyd, Apr 14 2016 EXAMPLE Illustration of a(2)=6:    11   12   12   12   11   11    22   12   22   11   12   21 Illustration of a few solutions of a(3):    111   112   122   111   111    121   111   112   212   111    111   111   222   222   222 CROSSREFS Cf. A068392, A271802, A068381, A068417, A113900. Sequence in context: A185148 A243921 A109092 * A221413 A145003 A248369 Adjacent sequences:  A068413 A068414 A068415 * A068417 A068418 A068419 KEYWORD nonn AUTHOR R. H. Hardin, Mar 02 2002 EXTENSIONS a(7)-a(14) from Andrew Howroyd, Apr 14 2016 STATUS approved

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Last modified August 15 10:12 EDT 2020. Contains 336492 sequences. (Running on oeis4.)