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A006782 Number of polygons of length 4n on L-lattice.
(Formerly M1930)
1
1, 0, 1, 2, 9, 36, 154, 684, 3128, 14666, 70258, 342766, 1698625, 8532410, 43368153, 222729492, 1154455161, 6033034032, 31760434883, 168311948410, 897327111964, 4810159375532 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

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=1..22.

Thorsten Ehlers, (C) simple generation algorithm

I. G. Enting and A. J. Guttmann, Self-avoiding polygons on the square, L and Manhattan lattices, J. Phys. A 18 (1985), 1007-1017.

CROSSREFS

Cf. A006781.

Sequence in context: A289805 A150967 A121769 * A150968 A073156 A150969

Adjacent sequences:  A006779 A006780 A006781 * A006783 A006784 A006785

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(13)-a(15) from Sean A. Irvine, Aug 01 2017

a(16)-a(21) from Thorsten Ehlers, Sep 30 2018

a(22) from Thorsten Ehlers, Nov 01 2018

STATUS

approved

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Last modified February 16 14:47 EST 2019. Contains 320163 sequences. (Running on oeis4.)