This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A160869 a(n) = sigma(6^(n-1)). 5
 1, 12, 91, 600, 3751, 22932, 138811, 836400, 5028751, 30203052, 181308931, 1088123400, 6529545751, 39179682372, 235085301451, 1410533397600, 8463265086751, 50779784492892, 304679288612371, 1828077476115000, 10968470088963751, 65810836228506612 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Colin Barker, Table of n, a(n) for n = 1..1000 J. H. Kwak and J. Lee, Enumeration of graph coverings, surface branched coverings and related group theory, in Combinatorial and Computational Mathematics (Pohang, 2000), ed. S. Hong et al., World Scientific, Singapore 2001, pp. 97-161. Index entries for linear recurrences with constant coefficients, signature (12,-47,72,-36). FORMULA a(n) = A059387(n)/2. - Vladimir Joseph Stephan Orlovsky, Apr 28 2010 a(n) = 12*a(n-1)-47*a(n-2)+72*a(n-3)-36*a(n-4). - Colin Barker, Nov 24 2014 G.f.: -x*(6*x^2-1) / ((x-1)*(2*x-1)*(3*x-1)*(6*x-1)). - Colin Barker, Nov 24 2014 a(n) = A000203(A000400(n-1)). - Michel Marcus, Sep 18 2018 MATHEMATICA Table[(2^n-1)*(3^n-1)/2, {n, 40}] (* Vladimir Joseph Stephan Orlovsky, Apr 28 2010 *) LinearRecurrence[{12, -47, 72, -36}, {1, 12, 91, 600}, 50] (* G. C. Greubel, Apr 30 2018 *) PROG (PARI) Vec(-x*(6*x^2-1)/((x-1)*(2*x-1)*(3*x-1)*(6*x-1)) + O(x^100)) \\ Colin Barker, Nov 24 2014 (PARI) for(n=1, 50, print1((2^n-1)*(3^n-1)/2, ", ")) \\ G. C. Greubel, Apr 30 2018 (MAGMA) [(2^n-1)*(3^n-1)/2: n in [1..50]]; // G. C. Greubel, Apr 30 2018 CROSSREFS Row 6 of array in A160870. Cf. A000203, A000400, A059387. Sequence in context: A001502 A001503 A004311 * A026074 A298397 A246585 Adjacent sequences:  A160866 A160867 A160868 * A160870 A160871 A160872 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Nov 15 2009 EXTENSIONS More terms from Vladimir Joseph Stephan Orlovsky, Apr 28 2010 More terms from Colin Barker, Nov 24 2014 Better definition from Altug Alkan, Oct 06 2015 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 May 24 18:34 EDT 2019. Contains 323534 sequences. (Running on oeis4.)