A168460 a(n) = 6 + 10*floor((n-1)/2).

6, 6, 16, 16, 26, 26, 36, 36, 46, 46, 56, 56, 66, 66, 76, 76, 86, 86, 96, 96, 106, 106, 116, 116, 126, 126, 136, 136, 146, 146, 156, 156, 166, 166, 176, 176, 186, 186, 196, 196, 206, 206, 216, 216, 226, 226, 236, 236, 246, 246, 256, 256, 266, 266, 276, 276, 286

Offset: 1

Author

Vincenzo Librandi, Nov 26 2009

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Crossrefs

Cf. A017341, A168283.

Programs

Magma

[6+10*Floor((n-1)/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013

Maple

A168460:=n->6 + 10*floor((n-1)/2): seq(A168460(n), n=1..100); # Wesley Ivan Hurt, Jul 24 2016

Mathematica

RecurrenceTable[{a[1]==6,a[n]==10n-a[n-1]-8},a,{n,80}] (* or *) LinearRecurrence[{1,1,-1},{6,6,16},80] (* Harvey P. Dale, Apr 25 2011 *)
Table[6 + 10 Floor[(n - 1)/2], {n, 70}] (* or *) CoefficientList[Series[2 (3 + 2 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)

Formula

a(n) = 10*n - a(n-1) - 8, with n>1, a(1)=6.

From R. J. Mathar, Jan 04 2011: (Start)

a(n) = 2*A168283(n).

a(n+1) = A017341(floor(n/2)).

G.f.: 2*x*(3 + 2*x^2) / ( (1+x)*(x-1)^2 ). (End)

a(n) = a(n-1) + a(n-2) - a(n-3) for n>3. - Vincenzo Librandi, Sep 19 2013

From G. C. Greubel, Jul 23 2016: (Start)

a(n) = (10*n - 5*(-1)^n - 3)/2.

E.g.f.: (1/2)*(-5 + 8*exp(x) + (10*x - 3)*exp(2*x))*exp(-x). (End)

a(n) = a(n-2) + 10 for n>2. - Wesley Ivan Hurt, Jul 24 2016

Extensions

New definition by Vincenzo Librandi, Sep 19 2013