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Number of hexaflexagons with 3n triangles that can be folded from a straight strip of paper.
(Formerly M3489)
3

%I M3489 #15 Nov 19 2022 01:10:34

%S 1,1,1,4,14,74,434,2876,19848,143306,1062149,8058223,62259820,

%T 488630360,3886211100,31267852668

%N Number of hexaflexagons with 3n triangles that can be folded from a straight strip of paper.

%D M. Kosters, A theory of hexaflexagons, Nieuw Archief Wisk., 17 (1999), 349-362.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%Y Cf. A001683, A000207.

%K nonn,more,nice

%O 1,4

%A _N. J. A. Sloane_, frb6006(AT)cs.rit.edu (Frank R. Bernhart)

%E More terms from Mike Godfrey (m.godfrey(AT)umist.ac.uk), Apr 02 2002