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Search: id:A100774
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| 0, 4, 16, 52, 160, 484, 1456, 4372, 13120, 39364, 118096, 354292, 1062880, 3188644, 9565936, 28697812, 86093440, 258280324, 774840976, 2324522932, 6973568800, 20920706404, 62762119216, 188286357652, 564859072960, 1694577218884
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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a(n) is the number of steps which are made when generating all n-step nonreversing random walks that begin in a fixed point P on a two-dimensional square lattice. To make one step means to move along one edge on the lattice.
a(n)=A048473(n)-1=A048473-A000012. [From Paul Curtz (bpcrtz(AT)free.fr), Jan 19 2009]
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FORMULA
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a(n)=2*(3^n - 1); a(0)=0, a(n)=4*Sum_{i = 0 to n-1} 3^i for n>0; a(n)=4*A003462
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MATHEMATICA
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a=0; lst={a}; Do[a=a*3+4; AppendTo[lst, a], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 25 2008]
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CROSSREFS
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Cf. A003462, A007051, A034472, A024023, A067771, A029858, A134931, A115099, A100774, A079004, A058481 [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 25 2008]
Sequence in context: A089093 A058234 A007688 this_sequence A107767 A087972 A074409
Adjacent sequences: A100771 A100772 A100773 this_sequence A100775 A100776 A100777
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KEYWORD
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easy,nonn
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AUTHOR
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Pawel P. Mazur (Pawel.Mazur(AT)pwr.wroc.pl), Apr 06 2005
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