The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A089264 Number of permutations of length n containing exactly once 132 and 213, likewise for pattern pair (231,312). 1
 3, 6, 17, 42, 102, 242, 564, 1296, 2944, 6624, 14784, 32768, 72192, 158208, 345088, 749568, 1622016, 3497984, 7520256, 16121856, 34471936, 73531392, 156499968, 332398592, 704643072, 1491075072, 3149922304, 6643777536, 13992198144 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,1 LINKS Table of n, a(n) for n=4..32. Aaron Robertson, Permutations restricted by two distinct patterns of length three, arXiv:math/0012029 [math.CO], 2000. Index entries for linear recurrences with constant coefficients, signature (6,-12,8). FORMULA For n>=7, a(n) = (n^2+21*n-28)*2^(n-9). G.f.: x^4*(x-1)^2*(2*x^3-2*x^2+6*x-3) / (2*x-1)^3. [Colin Barker, Jan 31 2013] MATHEMATICA LinearRecurrence[{6, -12, 8}, {3, 6, 17, 42, 102, 242}, 40] (* Harvey P. Dale, Apr 10 2022 *) CROSSREFS Cf. A001815. Sequence in context: A297972 A275057 A320807 * A121399 A212421 A238428 Adjacent sequences: A089261 A089262 A089263 * A089265 A089266 A089267 KEYWORD nonn,easy AUTHOR Ralf Stephan, Oct 30 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 27 12:27 EDT 2024. Contains 372858 sequences. (Running on oeis4.)