A168328 a(n) = 6 * floor( n/2 ).

0, 6, 6, 12, 12, 18, 18, 24, 24, 30, 30, 36, 36, 42, 42, 48, 48, 54, 54, 60, 60, 66, 66, 72, 72, 78, 78, 84, 84, 90, 90, 96, 96, 102, 102, 108, 108, 114, 114, 120, 120, 126, 126, 132, 132, 138, 138, 144, 144, 150, 150, 156, 156, 162, 162, 168, 168, 174, 174, 180, 180

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,1,-1)

Formula

a(n) = 6*n - a(n-1) - 6 for n>1, a(1)=0.

G.f.: 6*x^2/((1+x)*(1-x)^2). - Bruno Berselli, Sep 17 2013

a(n) = 6*A004526(n). Bruno Berselli, Sep 17 2013

E.g.f.: 3*(x*cosh(x) + (x - 1)*sinh(x)). - G. C. Greubel, Jul 18 2016

Mathematica

Table[6 Floor[n/2], {n, 70}] (* Bruno Berselli, Sep 18 2013 *)

Prog

(Magma) [n eq 1 select 0 else 6*n-Self(n-1)-6: n in [1..70]]; // Vincenzo Librandi, Sep 17 2013

Crossrefs

Cf. A004526, A008588.

Sequence in context: A340512 A338992 A055665 * A176569 A315778 A315779

Adjacent sequences: A168325 A168326 A168327 * A168329 A168330 A168331

Keyword

nonn,easy,less

Author

Vincenzo Librandi, Nov 23 2009

Extensions

G.f. adapted to the offset by Vincenzo Librandi, Sep 17 2013

New definition by Bruno Berselli, Sep 18 2013

Status

approved