This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A163438 Number of reduced words of length n in Coxeter group on 13 generators S_i with relations (S_i)^2 = (S_i S_j)^5 = I. 1
 1, 13, 156, 1872, 22464, 269490, 3232944, 38784174, 465276240, 5581708704, 66961236342, 803303685756, 9636871221978, 115609188148740, 1386911174446512, 16638146470934274, 199600322709006648 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The initial terms coincide with those of A170732, although the two sequences are eventually different. Computed with MAGMA using commands similar to those used to compute A154638. LINKS G. C. Greubel, Table of n, a(n) for n = 0..920 Index entries for linear recurrences with constant coefficients, signature (11, 11, 11, 11, -66). FORMULA G.f.: (t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(66*t^5 - 11*t^4 - 11*t^3 - 11*t^2 - 11*t + 1). MATHEMATICA CoefficientList[Series[(1+x)*(1-x^5)/(1-12*x+77*x^5-66*x^6), {x, 0, 10}], x] (* or *) LinearRecurrence[{11, 11, 11, 11, -66}, {1, 13, 156, 1872, 22464, 269490}, 30]] (* G. C. Greubel, Dec 23 2016 *) coxG[{5, 66, -11}] (* The coxG program is at A169452 *) (* G. C. Greubel, May 12 2019 *) PROG (PARI) my(x='x+O('x^30)); Vec((1+x)*(1-x^5)/(1-12*x+77*x^5-66*x^6)) \\ G. C. Greubel, Dec 23 2016 (MAGMA) R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (1+x)*(1-x^5)/(1-12*x+77*x^5-66*x^6) )); // G. C. Greubel, May 12 2019 (Sage) ((1+x)*(1-x^5)/(1-12*x+77*x^5-66*x^6)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 12 2019 CROSSREFS Sequence in context: A162768 A097827 A163084 * A163958 A164610 A164815 Adjacent sequences:  A163435 A163436 A163437 * A163439 A163440 A163441 KEYWORD nonn AUTHOR John Cannon and N. J. A. Sloane, Dec 03 2009 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 September 20 01:58 EDT 2019. Contains 327207 sequences. (Running on oeis4.)