cp's OEIS Frontend

A003104 Number of hexagonal n-element polyominoes whose graph is a path.

%I A003104 M1208 #35 May 07 2025 11:39:31
%S A003104 1,1,2,4,10,24,67,182,520,1474,4248,12196,35168,101226,291565,838764,
%T A003104 2412033,6929754,19896915,57084939,163677686,469008353,1343165478,
%U A003104 3844533186,10998790991,31451726513,89899650912,256859865260,733620238080,2094559523979,5978195451960
%N A003104 Number of hexagonal n-element polyominoes whose graph is a path.
%C A003104 In other words, number of 2-sided strip polyhexes with n cells.
%D A003104 E. M. Palmer, Variations of the cell growth problem, Lect. Notes Math. 303 (1972), 215-224.
%D A003104 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%D A003104 N. Trinajstić, S. Nikolić, J. V. Knop, W. R. Müller and K. Szymanski, Computational Chemical Graph Theory: Characterization, Enumeration, and Generation of Chemical Structures by Computer Methods, Ellis Horwood, 1991.
%H A003104 A. T. Balaban, J. Brunvoll, B. N. Cyvin & S. J. Cyvin, <a href="https://doi.org/10.1016/S0040-4020(01)85110-3">Enumeration of branched catacondensed benzenoid hydrocarbons and their numbers of Kekulé structures</a> Tetrahedron, 44(1) (1988), 221-228. See Table 1.
%H A003104 Wenchen He and Wenjie He, <a href="https://doi.org/10.1016/S0040-4020(01)82078-0">Generation and enumeration of planar polycyclic aromatic hydrocarbons</a>, Tetrahedron 42.19 (1986): 5291-5299. See Table 1, column B.
%H A003104 Ed Pegg, Jr., <a href="http://demonstrations.wolfram.com/PolyformExplorer/">Illustrations of polyforms</a>
%H A003104 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyhex.html">Polyhex</a>
%Y A003104 Cf. A323931, A323932.
%K A003104 nonn
%O A003104 1,3
%A A003104 _N. J. A. Sloane_
%E A003104 a(8)-a(12) from _Ed Pegg Jr_, May 13 2009
%E A003104 a(13)-a(19) from _Joseph Myers_, Nov 26 2010
%E A003104 a(20) from Trinajstić et al. (Table 4.2, the number of cata-condensed benzenoids with h hexagons, unbranched) added by _Andrey Zabolotskiy_, Feb 08 2023
%E A003104 a(21)-a(31) from _Bert Dobbelaere_, May 07 2025