This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A064837 a(n) = (6*n^4 + 30*n^3 - 20*n^2 + 14)*n/30 + (n mod 2). 2
 0, 2, 18, 114, 420, 1170, 2710, 5538, 10312, 17890, 29338, 45970, 69356, 101362, 144158, 200258, 272528, 364226, 479010, 620978, 794676, 1005138, 1257894, 1559010, 1915096, 2333346, 2821546, 3388114, 4042108, 4793266, 5652014 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Harry J. Smith, Table of n, a(n) for n = 0..500 G. L. Cohen and E. Tonkes, Dartboard arrangements, Elect. J. Combin., 8 (No. 2, 2001), #R4. Index entries for linear recurrences with constant coefficients, signature (5, -9, 5, 5, -9, 5, -1). FORMULA From R. J. Mathar, Dec 05 2008: (Start) a(n) = 2*A064838(n). G.f.: 2x*(1-x^5-2x^4+x^3+21x^2+4x)/((1-x)^6*(1+x)). (End) a(0)=0, a(1)=2, a(2)=18, a(3)=114, a(4)=420, a(5)=1170, a(6)=2710, a(n) = 5*a(n-1) - 9*a(n-2) + 5*a(n-3) + 5*a(n-4) - 9*a(n-5) + 5*a(n-6) - a(n-7). - Harvey P. Dale, Sep 15 2014 MATHEMATICA Table[(6n^4+30n^3-20n^2+14) n/30+Mod[n, 2], {n, 0, 30}] (* or *) LinearRecurrence[ {5, -9, 5, 5, -9, 5, -1}, {0, 2, 18, 114, 420, 1170, 2710}, 40] (* Harvey P. Dale, Sep 15 2014 *) PROG (PARI) { for (n=0, 500, a=(6*n^4 + 30*n^3 - 20*n^2 + 14)*n/30 + n%2; write("b064837.txt", n, " ", a) ) } \\ Harry J. Smith, Sep 28 2009 CROSSREFS Sequence in context: A112328 A038721 A308700 * A224902 A027433 A153338 Adjacent sequences:  A064834 A064835 A064836 * A064838 A064839 A064840 KEYWORD nonn AUTHOR N. J. A. Sloane, Oct 25 2001 EXTENSIONS Better description from Frank Ellermann, Mar 16 2002 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 October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)