This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A009946 Coordination sequence for NiAs(2), Ni position. 1
 1, 6, 20, 42, 74, 114, 164, 222, 290, 366, 452, 546, 650, 762, 884, 1014, 1154, 1302, 1460, 1626, 1802, 1986, 2180, 2382, 2594, 2814, 3044, 3282, 3530, 3786, 4052, 4326, 4610, 4902, 5204, 5514, 5834, 6162, 6500, 6846, 7202, 7566, 7940, 8322, 8714 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES Gmelin Handbook of Inorg. and Organomet. Chem., 8th Ed., 1994, TYPIX search code (194) hP4. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 R. W. Grosse-Kunstleve, Coordination Sequences and Encyclopedia of Integer Sequences R. W. Grosse-Kunstleve, G. O. Brunner and N. J. A. Sloane, Algebraic Description of Coordination Sequences and Exact Topological Densities for Zeolites, Acta Cryst., A52 (1996), pp. 879-889. Reticular Chemistry Structure Resource, acs Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1). FORMULA a(0)=1, a(4n)=2*((6n)^2+1), a(4n+2)=18*(2n+1)^2+2, a(2n+1)=6*(3n^2+3n+1). - Ralf Stephan, Mar 07 2004 From Colin Barker, Aug 31 2013: (Start) a(n) = (7+(-1)^n+18*n^2)/4 for n>0. a(n) = 2*a(n-1)-2*a(n-3)+a(n-4) for n>4. G.f.: -(x^4+4*x^3+8*x^2+4*x+1) / ((x-1)^3*(x+1)). (End) MATHEMATICA CoefficientList[Series[-(x^4 + 4 x^3 + 8 x^2 + 4 x + 1)/((x - 1)^3 (x + 1)), {x, 0, 50}], x] (* Vincenzo Librandi, Oct 15 2013 *) PROG (PARI) Vec(-(x^4+4*x^3+8*x^2+4*x+1)/((x-1)^3*(x+1)) + O(x^100)) \\ Colin Barker, Aug 31 2013 CROSSREFS Sequence in context: A077539 A002943 A068377 * A290154 A094274 A094279 Adjacent sequences:  A009943 A009944 A009945 * A009947 A009948 A009949 KEYWORD nonn,easy AUTHOR 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 19 11:09 EDT 2019. Contains 328216 sequences. (Running on oeis4.)