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A009927 Coordination sequence for Cr3Si, Si position. 4
1, 12, 50, 120, 218, 344, 546, 728, 902, 1212, 1526, 1784, 2154, 2552, 2954, 3432, 3854, 4340, 4998, 5504, 6002, 6768, 7442, 8024, 8814, 9572, 10334, 11232, 11978, 12824, 13938, 14768, 15590, 16812, 17846, 18752, 19962, 21080, 22202, 23520 (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 (223) cP8.

LINKS

R. W. Grosse-Kunstleve, Table of n, a(n) for n = 0..1000

V. A. Blatov, A. P. Shevchenko, D. M. Proserpio, Applied Topological Analysis of Crystal Structures with the Program Package ToposPro, Cryst. Growth Des. 2014, 14, 3576-3586. See Table I.

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.

FORMULA

G.f.: (1+12*x+51*x^2+130*x^3+243*x^4+350*x^5+450*x^6+418*x^7 +327*x^8+182*x^9+51*x^10+16*x^11-7*x^12+8*x^13+12*x^14)/ ((1+x)*(1+x^2)^2*(1+x+x^2)^2*(1-x)^3). - Robert Israel, Dec 18 2015

Empirical: a(n) = (1903/72) + (3/8)*(-1)^n + 19*KroneckerDelta[n,0] - 8*KroneckerDelta[n,1] - 12*KroneckerDelta[n,2] + ((n+1)/12)*(187*n-273) - (32*sqrt(3)/27)*((13/2)*cos((4n+1)*Pi/6) + sin(2n*Pi/3)) - (3*sqrt(26)/2)*(-1)^n*cos(n*Pi/2 + arctan(1/5)) - (3/4)*i^n*(1+(-1)^n)*(n+2). - G. C. Greubel, Dec 18 2015

G.f.: (1 + 12*x + 50*x^2 + 118*x^3 + 192*x^4 + 220*x^5 + 207*x^6 + 68*x^7-123*x^8-236*x^9-276*x^10-166*x^11-58*x^12-8*x^13 + 19*x^14-8*x^15-12*x^16) / (1-x^3)^2 / (1-x^4)^2. - Sean A. Irvine, Mar 15 2018

CROSSREFS

Sequence in context: A009930 A066644 A009934 * A009938 A063491 A248230

Adjacent sequences:  A009924 A009925 A009926 * A009928 A009929 A009930

KEYWORD

nonn

AUTHOR

Ralf W. Grosse-Kunstleve

STATUS

approved

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Last modified August 17 09:30 EDT 2018. Contains 313814 sequences. (Running on oeis4.)