cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A079997 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={0}.

Original entry on oeis.org

1, 0, 1, 2, 9, 24, 57, 140, 376, 1016, 2692, 7020, 18369, 48344, 127465, 335510, 882081, 2319136, 6100393, 16049440, 42220168, 111053856, 292109320, 768373144, 2021186393, 5316647448, 13985104873, 36786882378, 96765680857, 254536684328
Offset: 0

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Author

Vladimir Baltic, Feb 17 2003

Keywords

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.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,3,0,6,10,0,-12,-10,-2,0,0,-1,1,1},{1,0,1,2,9,24,57,140,376,1016,2692,7020,18369,48344},40] (* Harvey P. Dale, Nov 27 2013 *)

Formula

a(n) = a(n-1)+3*a(n-2)+6*a(n-4)+10*a(n-5)-12*a(n-7)-10*a(n-8)-2*a(n-9)-a(n-12)+a(n-13)+a(n-14)
G.f.: -(x^8+x^7-x^5-2*x^4+x^3-2*x^2-x+1)/(x^14 +x^13 -x^12 -2*x^9 -10*x^8 -12*x^7 +10*x^5 +6*x^4 +3*x^2 +x-1).