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 A003203 Cluster series for square lattice. (Formerly M3433) 16
 1, 4, 12, 24, 52, 108, 224, 412, 844, 1528, 3152, 5036, 11984, 15040, 46512, 34788, 197612, 4036, 929368, -702592, 4847552, -7033956, 27903296, -54403996, 170579740 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The word "cluster" here essentially means polyomino or animal. This sequence can be computed based on a calculation of the perimeter polynomials of polyominoes. In particular, if P_n(x) is the perimeter polynomial for all fixed polyominoes of size n, then this sequence is the coefficients of x in Sum_{k>=1} k^2 * x^k * P_k(1-x). - Sean A. Irvine, Aug 15 2020 REFERENCES J. W. Essam, Percolation and cluster size, in C. Domb and M. S. Green, Phase Transitions and Critical Phenomena, Ac. Press 1972, Vol. 2; see especially pp. 225-226. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Table of n, a(n) for n=0..24. John Adler, Series Expansions, Computers in Physics, 8 (1994), 287-295. A. R. Conway and A. J. Guttmann, On two-dimensional percolation, J. Phys. A: Math. Gen., 28 (1995), 891-904. See Table 3. Sean A. Irvine, Java program (github) M. F. Sykes and J. W. Essam, Critical percolation probabilities by series methods, Phys. Rev., 133 (1964), A310-A315. M. F. Sykes and M. Glen, Percolation processes in two dimensions. I. Low-density series expansions, J. Phys. A: Math. Gen., 9 (1976), 87-95. CROSSREFS Cf. A001168, A003202 (triangular net), A003204 (honeycomb net), A003198 (bond percolation), A338210 (perimeter polynomials). Sequence in context: A143270 A037338 A136486 * A051193 A356550 A216244 Adjacent sequences: A003200 A003201 A003202 * A003204 A003205 A003206 KEYWORD sign,more AUTHOR N. J. A. Sloane EXTENSIONS a(11)-a(14) from Sean A. Irvine, Aug 15 2020 a(15)-a(24) added from Conway & Guttmann by Andrey Zabolotskiy, Feb 01 2022 STATUS approved

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