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A001884 Hit polynomials.
(Formerly M2117 N0835)
2
1, 0, 1, 2, 20, 104, 775, 6140, 55427, 553802, 6087992, 72994152, 948103477, 13262133736, 198769630061, 3177862894922, 53984653965996, 971068821144112, 18438722595913195, 368558842844143268, 7735520783692157215, 170095060428041137778, 3910332719957508452016, 93806427360751009531632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

J. Riordan, The enumeration of permutations with three-ply staircase restrictions, unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963.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).

LINKS

Table of n, a(n) for n=1..24.

N. J. A. Sloane, Annotated copy of Riordan's Three-Ply Staircase paper (unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963)

CROSSREFS

Second column of A080018.

Cf. A001883-A001891.

Sequence in context: A267678 A009357 A052361 * A028477 A073077 A069537

Adjacent sequences:  A001881 A001882 A001883 * A001885 A001886 A001887

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Vladeta Jovovic and Vladimir Baltic, Jan 20 2003

a(21)-a(24) from Vaclav Kotesovec, Oct 10 2017

STATUS

approved

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Last modified October 18 10:59 EDT 2019. Contains 328147 sequences. (Running on oeis4.)