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A008255
Coordination sequence T2 for feldspar.
1
1, 4, 10, 22, 38, 56, 82, 112, 142, 182, 226, 268, 322, 380, 434, 502, 574, 640, 722, 808, 886, 982, 1082, 1172, 1282, 1396, 1498, 1622, 1750, 1864, 2002, 2144, 2270, 2422, 2578, 2716, 2882, 3052, 3202, 3382, 3566, 3728, 3922, 4120, 4294, 4502, 4714, 4900
OFFSET
0,2
FORMULA
a(3*m) = 20*m^2+2, a(3*m+1) = 20*m^2+14*m+4, a(3*m+2) = 20*m^2+26*m+10.
G.f.: (1+x)^3*(1+3*x^2+x^4) / ((1-x)^3*(1+x+x^2)^2). - Colin Barker, Dec 22 2015
MATHEMATICA
Table[SeriesCoefficient[(1 + x)^3 (1 + 3 x^2 + x^4)/((1 - x)^3 (1 + x + x^2)^2), {x, 0, n}], {n, 0, 47}] (* Michael De Vlieger, Dec 22 2015 *)
Join[{1}, LinearRecurrence[{1, 0, 2, -2, 0, -1, 1}, {4, 10, 22, 38, 56, 82, 112}, 50]] (* Vincenzo Librandi, Dec 23 2015 *)
PROG
(PARI) Vec((1+x)^3*(1+3*x^2+x^4)/((1-x)^3*(1+x+x^2)^2) + O(x^100)) \\ Colin Barker, Dec 22 2015
CROSSREFS
Sequence in context: A009891 A301077 A341734 * A008031 A339609 A008248
KEYWORD
nonn,easy
AUTHOR
Georg Thimm (mgeorg(AT)ntu.edu.sg) and Ralf W. Grosse-Kunstleve
STATUS
approved