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Search: id:A131891
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A131891 a(n) is the number of shapes of balanced trees with constant branching factor 5 and n nodes. The node is balanced if the size, measured in nodes, of each pair of its children differ by at most one node. +0
5
1, 5, 10, 10, 5, 1, 25, 250, 1250, 3125, 3125, 31250, 125000, 250000, 250000, 100000, 500000, 1000000, 1000000, 500000, 100000, 250000, 250000, 125000, 31250, 3125, 3125, 1250, 250, 25, 1 (list; graph; listen)
OFFSET

1,2

LINKS

Jeffrey A. Barnett Counting Balanced Tree Shapes.

FORMULA

a(0) = a(1) = 1; a(5n+1+m) = (5 choose m) * a(n+1)^m * a(n)^(5-m), where n >= 0 and 0 <= m <= 5.

CROSSREFS

Cf. A110316, A131889, A131890, A131892, A131893.

Adjacent sequences: A131888 A131889 A131890 this_sequence A131892 A131893 A131894

Sequence in context: A001483 A087109 A063261 this_sequence A062986 A065755 A135912

KEYWORD

easy,nonn

AUTHOR

Jeffrey A. Barnett (jbb(AT)notatt.com), Jul 24 2007

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.


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