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Search: id:A046995
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| A046995 |
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Greek-key tours on a 4 X n board; i.e. self-avoiding walks on 4 X n grid starting in top left corner. |
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+0
6
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| 1, 4, 17, 52, 160, 469, 1337, 3750, 10347, 28249, 76382, 204996, 546651, 1449952, 3828232, 10067585, 26384939, 68941126, 179658343, 467084601, 1211812016, 3138075544, 8112667259, 20941558268, 53983767498
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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Posting by Thomas Womack (mert0236(AT)sable.ox.ac.uk) to sci.math newsgroup, Apr 21 1999.
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FORMULA
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Conjecture: a(n)=3a(n-1)+3a(n-2)-9a(n-3)-6a(n-4)+5a(n-5)+a(n-6)-3a(n-7)+a(n-8) for n>=10. - Dean Hickerson (dean.hickerson(AT)yahoo.com), Apr 05 2003
Conjecture: G.f.: x*(-(x-1)*(x^7-x^6-2*x^5+3*x^4-2*x^3-4*x^2-2*x-1))/((x^4-2*x^3+2*x^2+2*x-1)*(x^4-x^3-3*x^2-x+1)) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009]
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CROSSREFS
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Cf. A046994.
Sequence in context: A131339 A047668 A092091 this_sequence A001585 A060262 A157492
Adjacent sequences: A046992 A046993 A046994 this_sequence A046996 A046997 A046998
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KEYWORD
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nonn,walk
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AUTHOR
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Antreas P. Hatzipolakis (xpolakis(AT)otenet.gr)
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EXTENSIONS
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More terms from Hugo van der Sanden (hv(AT)crypt.org), Apr 02 2003
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