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 A305324 Number of one-sided 'divisible' polyominoes of size 2^(n-1), where a 'divisible' polyomino is either a monomino (square) or a polyomino which can be separated into two identical 'divisible' polyominoes. 0
 1, 1, 6, 90, 3356, 232283, 27964488 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) is nonzero for any n >= 1. Proof is trivial by induction. a(n) <= A000988(2^(n-1)) as any polyomino counted here is also counted in A000988. LINKS EXAMPLE For n = 3 (polyominoes of size 4), the 'divisible' polyominoes are the I, O, J, L, S and Z tetrominoes. The T tetromino is not 'divisible'. CROSSREFS Cf. A000988. Sequence in context: A232979 A218758 A219304 * A265088 A077370 A226382 Adjacent sequences: A305321 A305322 A305323 * A305325 A305326 A305327 KEYWORD nonn,more AUTHOR Josh Marza, May 30 2018 EXTENSIONS Definition changed and more terms added by John Mason, Sep 20, 2022 STATUS approved

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Last modified March 20 20:37 EDT 2023. Contains 361391 sequences. (Running on oeis4.)