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A001889
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Hit polynomials.
(Formerly M3345 N1346)
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1
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1, 4, 8, 38, 209, 1400, 10849, 95516, 938441, 10179149, 120748974, 1554688240, 21588485677, 321561688748, 5113709884902, 86469576394028, 1549114961438599, 29309613834899864, 583986501706555597
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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REFERENCES
| J. Riordan, ``The enumeration of permutations with three-ply staircase restrictions,'' unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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CROSSREFS
| Third column of A080061.
Sequence in context: A032213 A032317 A032226 * A032138 A032151 A032042
Adjacent sequences: A001886 A001887 A001888 * A001890 A001891 A001892
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Vladeta Jovovic, Vladimir Baltic, (vladeta(AT)eunet.rs), Jan 23 2003
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