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A001884
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Hit polynomials.
(Formerly M2117 N0835)
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1
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1, 0, 1, 2, 20, 104, 775, 6140, 55427, 553802, 6087992, 72994152, 948103477, 13262133736, 198769630061, 3177862894922, 53984653965996, 971068821144112, 18438722595913195, 368558842844143268
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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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| J. Riordan, ``The enumeration of permutations with three-ply staircase restrictions,'' unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963.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
| Second column of A080018.
Sequence in context: A103101 A009357 A052361 * A028477 A073077 A069537
Adjacent sequences: A001881 A001882 A001883 * A001885 A001886 A001887
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KEYWORD
| nonn,more
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Vladeta Jovovic and Vladimir Baltic (vladeta(AT)eunet.rs), Jan 20 2003
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