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 A188494 Number of permutations p on the set [n] with the properties that abs(p(i)-i) <= 3 for all i and p(1) <= 2. 7
 0, 1, 2, 4, 12, 42, 138, 414, 1235, 3764, 11604, 35664, 109132, 333652, 1021220, 3127709, 9578526, 29326904, 89785684, 274896606, 841682902, 2577075290, 7890425175, 24158602552, 73968049928, 226473538032, 693411153800, 2123068036904, 6500352097064 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS 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 zeros in the (3,1) and (4,1)-entries), and is zero elsewhere. This is row 8 of Kløve's Table 3. LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000(first 93 terms from Nathaniel Johnston) Torleiv Kløve, Spheres of Permutations under the Infinity Norm - Permutations with limited displacement, Reports in Informatics, Department of Informatics, University of Bergen, Norway, no. 376, November 2008. Index entries for linear recurrences with constant coefficients, signature (1,3,3,13,21,19,3,-7,-9,-5,-3,-3,-1). FORMULA From Nathaniel Johnston, Apr 10 2011: (Start) a(n) = A188491(n+1) - A002528(n) - A002526(n). a(n) = A002526(n-1) + A002527(n-1). (End) G.f.: x*(x^6 +x^5 -x^4 -x^3 -x^2 +x +1) / (x^13 +3*x^12 +3*x^11 +5*x^10 +9*x^9 +7*x^8 -3*x^7 -19*x^6 -21*x^5 -13*x^4 -3*x^3 -3*x^2 -x +1). - Colin Barker, Dec 13 2014 MAPLE with(LinearAlgebra): A188494:= n-> `if`(n=0, 0, Permanent(Matrix(n, (i, j)->               `if`(abs(j-i)<4 and [i, j]<>[3, 1] and [i, j]<>[4, 1], 1, 0)))): seq(A188494(n), n=0..20); MATHEMATICA LinearRecurrence[{1, 3, 3, 13, 21, 19, 3, -7, -9, -5, -3, -3, -1}, {0, 1, 2, 4, 12, 42, 138, 414, 1235, 3764, 11604, 35664, 109132}, 30] (* Harvey P. Dale, Dec 27 2015 *) PROG (PARI) concat(0, Vec(x*(x^6 +x^5 -x^4 -x^3 -x^2 +x +1) / (x^13 +3*x^12 +3*x^11 +5*x^10 +9*x^9 +7*x^8 -3*x^7 -19*x^6 -21*x^5 -13*x^4 -3*x^3 -3*x^2 -x +1) + O(x^100))) \\ Colin Barker, Dec 13 2014 CROSSREFS Sequence in context: A244035 A126942 A126947 * A202668 A200222 A063179 Adjacent sequences:  A188491 A188492 A188493 * A188495 A188496 A188497 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Apr 01 2011 EXTENSIONS Name and comments edited, and a(12)-a(28) from Nathaniel Johnston, Apr 10 2011 STATUS approved

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Last modified October 21 20:44 EDT 2019. Contains 328315 sequences. (Running on oeis4.)