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A163989
First differences of A160379.
1
1, 26, 8, 200, 26, 620, 56, 1304, 98, 2252, 152, 3464, 218, 4940, 296, 6680, 386, 8684, 488, 10952, 602, 13484, 728, 16280, 866, 19340, 1016, 22664, 1178, 26252, 1352, 30104, 1538, 34220, 1736, 38600, 1946, 43244, 2168, 48152, 2402, 53324, 2648, 58760, 2906
OFFSET
1,2
FORMULA
a(2n+1) = 6n^2 + 2 for n>=1.
a(2n) = 132n^2 - 240n + 152 for n>=2.
From Colin Barker, Sep 17 2013: (Start)
a(n) = 3*a(n-2)-3*a(n-4)+a(n-6) for n>8.
G.f.: -x*(18*x^3+x^2+26*x+1)*(x^4+4*x^2+1) / ((x-1)^3*(x+1)^3). (End)
PROG
(PARI) Vec(-x*(18*x^3+x^2+26*x+1)*(x^4+4*x^2+1)/((x-1)^3*(x+1)^3) + O(x^100)) \\ Colin Barker, Sep 17 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, Sep 20 2009
EXTENSIONS
Formula and more terms from Nathaniel Johnston, Nov 15 2010
More terms from Colin Barker, Sep 17 2013
STATUS
approved