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A168461
a(n) = 10*floor(n/2).
1
0, 10, 10, 20, 20, 30, 30, 40, 40, 50, 50, 60, 60, 70, 70, 80, 80, 90, 90, 100, 100, 110, 110, 120, 120, 130, 130, 140, 140, 150, 150, 160, 160, 170, 170, 180, 180, 190, 190, 200, 200, 210, 210, 220, 220, 230, 230, 240, 240, 250, 250, 260, 260, 270, 270, 280
OFFSET
1,2
FORMULA
a(n) = 10*n - a(n-1) - 10, with n>1, a(1)=0.
a(n) = 10*floor(n/2) = A168437(n) - 3. - Rick L. Shepherd, Jun 17 2010
G.f.: 10*x^2/((1+x)*(x-1)^2). - Vincenzo Librandi, Sep 19 2013
a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 19 2013
From G. C. Greubel, Jul 23 2016: (Start)
a(n) = (5/2)*(2*n + (-1)^n - 1).
E.g.f.: (5/2)*(1 +(2*x - 1)*exp(2*x))*exp(-x). (End)
MAPLE
A168461:=n->10*floor(n/2); seq(A168461(n), n=1..100); # Wesley Ivan Hurt, Nov 25 2013
MATHEMATICA
Table[10 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[10 x/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {0, 10, 10}, 60] (* Harvey P. Dale, Mar 02 2024 *)
PROG
(Magma) [10*Floor(n/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013
CROSSREFS
Bisections are A008592 and (A008592 MINUS {0}). - Rick L. Shepherd, Jun 17 2010
Sequence in context: A331057 A205724 A040091 * A309464 A368362 A022093
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 26 2009
EXTENSIONS
Edited by Rick L. Shepherd, Jun 17 2010
Definition rewritten, using Shepherd's formula, by Vincenzo Librandi, Sep 19 2013
STATUS
approved