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A007549
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Number of increasing rooted connected graphs where every block is a complete graph.
(Formerly M2977)
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6
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1, 1, 3, 14, 89, 716, 6967, 79524, 1041541, 15393100, 253377811, 4596600004, 91112351537, 1959073928124, 45414287553455, 1129046241331316, 29965290866974493, 845605519848379436, 25282324544244718411
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| In an increasing rooted graph, nodes are numbered and the numbers increase as you move away from the root.
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REFERENCES
| N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210.
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FORMULA
| Shifts left when exponentiated twice.
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MAPLE
| exptr:= proc (p) local g; g:= proc(n) option remember; p(n) +add (binomial (n-1, k-1) *p(k) *g(n-k), k=1..n-1) end: end: b:= exptr (exptr (a)): a:= n-> `if` (n=0, 1, b(n-1)): seq (a(n), n=1..30); # Alois P. Heinz, Oct 07 2008
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CROSSREFS
| Cf. A007563, A030019, A035051-A035053.
Sequence in context: A199548 A038170 A007840 * A081005 A074518 A200317
Adjacent sequences: A007546 A007547 A007548 * A007550 A007551 A007552
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KEYWORD
| nonn,eigen,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| New description from Christian G. Bower (bowerc(AT)usa.net), Oct 15 1998.
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