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A002527
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Number of permutations p on the set [n] with the properties that abs(p(i)-i) <= 3 for all i and p(1) <= 3.
(Formerly M1626 N0637)
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12
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0, 1, 2, 6, 18, 60, 184, 560, 1695, 5200, 15956, 48916, 149664, 458048, 1402360, 4294417, 13149210, 40259178, 123260854, 377395940, 1155508592, 3537919648, 10832298239, 33165996032, 101546731816, 310913195800, 951945967120, 2914642812096, 8923975209168
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OFFSET
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0,3
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COMMENTS
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a(n) is also the permanent of the n X n matrix that has ones on its diagonal, ones on its three superdiagonals, ones on its three subdiagonals (with the exception of a single zero in the (4,1)-entry), and is zero elsewhere.
This is the second row of Kløve's Table 3.
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REFERENCES
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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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Index entries for linear recurrences with constant coefficients, signature (2,2,0,10,8,-2,-16,-10,-2,4,2,0,2,1).
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FORMULA
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G.f.: x*(x^7+2*x^6-2*x^4-2*x^3-1) / (x^14 +2*x^13 +2*x^11 +4*x^10 -2*x^9 -10*x^8 -16*x^7 -2*x^6 +8*x^5 +10*x^4 +2*x^2 +2*x-1). - Alois P. Heinz, Apr 07 2011
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MAPLE
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with(LinearAlgebra):
A002527:= n-> `if`(n=0, 0, Permanent(Matrix(n, (i, j)->
`if`(abs(j-i)<4 and [i, j]<>[4, 1], 1, 0)))):
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MATHEMATICA
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A002527[n_] := If [n == 0, 0, Permanent[Table[If [Abs[j-i]<4 && {i, j} != {4, 1}, 1, 0], {i, 1, n}, {j, 1, n}]]]; Table [A002527[n], {n, 0, 25}] (* Jean-François Alcover, Mar 11 2014, after Maple *)
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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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