The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A079960 Number of permutations satisfying -k <= p(i) - i <= r and p(i) - i not in I, i=1..n, with k=1, r=5, I={2,3}. 0
 1, 1, 2, 3, 5, 9, 16, 28, 49, 85, 148, 258, 450, 785, 1369, 2387, 4162, 7257, 12654, 22065, 38475, 67089, 116983, 203983, 355685, 620208, 1081457, 1885737, 3288160, 5733565, 9997618, 17432848, 30397660, 53004405, 92423790, 161159378 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Number of compositions (ordered partitions) of n into elements of the set {1,2,5,6}. 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 Milan Janjic, Binomial Coefficients and Enumeration of Restricted Words, Journal of Integer Sequences, 2016, Vol 19, #16.7.3 Index entries for linear recurrences with constant coefficients, signature (1,1,0,0,1,1). FORMULA a(n) = a(n-1) + a(n-2) + a(n-5) + a(n-6). G.f.: -1/(x^6 + x^5 + x^2 + x - 1). MAPLE g:=1/(1-z-z^2-z^5-z^6): gser:=series(g, z=0, 49): seq((coeff(gser, z, n)), n=0..35); # Zerinvary Lajos, Apr 17 2009 CROSSREFS Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014. Sequence in context: A137402 A134009 A018160 * A005314 A099529 A088352 Adjacent sequences:  A079957 A079958 A079959 * A079961 A079962 A079963 KEYWORD nonn,easy AUTHOR Vladimir Baltic, Feb 19 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 10 06:20 EDT 2020. Contains 333392 sequences. (Running on oeis4.)