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 A008000 Coordination sequence T1 for Zeolite Code ABW and ATN. 793
 1, 4, 10, 21, 36, 54, 78, 106, 136, 173, 214, 256, 306, 360, 414, 477, 544, 610, 686, 766, 844, 933, 1026, 1116, 1218, 1324, 1426, 1541, 1660, 1774, 1902, 2034, 2160, 2301, 2446, 2584, 2738, 2896, 3046, 3213, 3384, 3546, 3726, 3910, 4084, 4277, 4474, 4660 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES W. M. Meier, D. H. Olson and Ch. Baerlocher, Atlas of Zeolite Structure Types, 4th Ed., Elsevier, 1996 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. International Zeolite Association, Database of Zeolite Structures Index entries for linear recurrences with constant coefficients, signature (1,0,2,-2,0,-1,1). FORMULA a(3m)=19m^2+2, a(3m+1)=19m^2+13m+4, a(3m+2)=19m^2+25m+10, for m>0. [N. J. A. Sloane] G.f.: (1+3*x+6*x^2+9*x^3+9*x^4+6*x^5+3*x^6+x^7)/((1-x)^3*(1+x+x^2)^2). [Vladimir Joseph Stephan Orlovsky] MATHEMATICA CoefficientList[Series[(-z^7 - 3 z^6 - 6 z^5 - 9 z^4 - 9 z^3 - 6 z^2 - 3 z - 1)/((z - 1)^3 (z^2 + z + 1)^2), {z, 0, 100}], z] (* Vladimir Joseph Stephan Orlovsky, Jun 27 2011 *) PROG (PARI) a(n)=if(n, my(m=divrem(n, 3)); 19*m[1]^2+if(m[2], if(m[2]==1, 13*m[1]+4, 25*m[1]+10), 2), 1) \\ Charles R Greathouse IV, Jun 28 2011 (MAGMA) I:=[1, 4, 10, 21, 36, 54, 78, 106]; [n le 8 select I[n] else Self(n-1)+2*Self(n-3)-2*Self(n-4)-Self(n-6)+Self(n-7): n in [1..50]]; // Vincenzo Librandi, Jun 10 2013 CROSSREFS Sequence in context: A009894 A301013 A027370 * A038408 A038411 A033599 Adjacent sequences:  A007997 A007998 A007999 * A008001 A008002 A008003 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified May 12 17:19 EDT 2021. Contains 343829 sequences. (Running on oeis4.)