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Search: id:A072638
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| A072638 |
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Number of unary-binary rooted trees of height at most n. |
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7
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| 0, 1, 3, 10, 66, 2278, 2598060, 3374961778891, 5695183504492614029263278, 16217557574922386301420536972254869595782763547560, 131504586847961235687181874578063117114329409897615188504091716162522225834932122128288032336298141
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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A unary-binary tree is one in which the degree of every node is <= 3.
Apparently a(n)=A006894(n+1)-1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2007
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LINKS
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Index entries for sequences related to rooted trees
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FORMULA
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a(n+1)=1+(a(n)*(a(n)+3))/2.
Conjecture: a(n)=A006894(n+1)-1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 23 2007
a(n):=C(a(n-1)+2,2),n>=-1. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 08 2007
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MAPLE
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a[ -1]:=0:a[0]:=1:for n from 1 to 50 do a[n]:=binomial(a[n-1]+2, 2) od: seq(a[n], n=-1..9); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 08 2007
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CROSSREFS
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Maximal position in A071673 where the value n occurs.
Binary width of each term: A072641. Cf. A072639, A072640, A072654.
Adjacent sequences: A072635 A072636 A072637 this_sequence A072639 A072640 A072641
Sequence in context: A041014 A009400 A004102 this_sequence A080526 A002499 A047833
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KEYWORD
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nonn
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AUTHOR
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Antti Karttunen Jun 02 2002
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EXTENSIONS
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Edited by Christian G. Bower (bowerc(AT)usa.net), Oct 23 2002
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