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 A079986 Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=3, r=3, I={-2,0,2}. 0
 1, 0, 1, 0, 4, 0, 16, 0, 49, 0, 169, 0, 576, 0, 1936, 0, 6561, 0, 22201, 0, 75076, 0, 254016, 0, 859329, 0, 2907025, 0, 9834496, 0, 33269824, 0, 112550881, 0, 380757169, 0, 1288092100, 0, 4357584144, 0, 14741602225 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS a(n)=( A000073(k+2) )^2 if n=2k, a(n)=0 otherwise. REFERENCES D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), pp. 755-770. North-Holland, Amsterdam, 1970. LINKS Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (2010), 119-135 Index entries for linear recurrences with constant coefficients, signature (0, 2, 0, 3, 0, 6, 0, -1, 0, 0, 0, -1). FORMULA a(n) = 2*a(n-2)+3*a(n-4)+6*a(n-6)-a(n-8)-a(n-12). G.f.: -(x^6+x^4+x^2-1)/(x^12+x^8-6*x^6-3*x^4-2*x^2+1) MATHEMATICA LinearRecurrence[{0, 2, 0, 3, 0, 6, 0, -1, 0, 0, 0, -1}, {1, 0, 1, 0, 4, 0, 16, 0, 49, 0, 169, 0}, 50] (* Harvey P. Dale, Nov 03 2015 *) CROSSREFS Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014. Sequence in context: A059065 A170771 A170772 * A134746 A210067 A199572 Adjacent sequences:  A079983 A079984 A079985 * A079987 A079988 A079989 KEYWORD nonn AUTHOR Vladimir Baltic, Feb 17 2003 STATUS approved

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Last modified June 22 21:29 EDT 2021. Contains 345393 sequences. (Running on oeis4.)