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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, 12222118836543561940, 268060239251978779839, 6148136982942476816891
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OFFSET
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2,2
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REFERENCES
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J. Riordan, The enumeration of permutations with three-ply staircase restrictions, unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963. (See A001883)
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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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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