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A007558
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Shifts 2 places left when e.g.f. is squared.
(Formerly M1230)
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2
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1, 1, 1, 2, 4, 10, 30, 100, 380, 1600, 7400, 37400, 204600, 1205600, 7612000, 51260000, 366784000, 2778820000, 22222332000, 187067320000, 1653461480000, 15310662400000, 148217381840000, 1497226615280000, 15754506226800000, 172407188412800000
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..200
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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MAPLE
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a:= proc(n) option remember;
`if`(n<2, 1, add(a(i)*a(n-2-i) *binomial(n-2, i), i=0..n-2))
end:
seq (a(n), n=0..30); # Alois P. Heinz, Jun 22 2012
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CROSSREFS
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Sequence in context: A149836 A003289 A087161 * A094957 A000733 A092073
Adjacent sequences: A007555 A007556 A007557 * A007559 A007560 A007561
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KEYWORD
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nonn,nice,eigen
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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