A169721 a(n) = (2*(3*2^(n-1)-1))^2.

1, 16, 100, 484, 2116, 8836, 36100, 145924, 586756, 2353156, 9424900, 37724164, 150945796, 603881476, 2415722500, 9663283204, 38653919236, 154617249796, 618472144900, 2473894871044, 9895592067076, 39582393434116, 158329624068100, 633318596935684

Offset

0,2

Comments

A subsequence of the squares (A000290).

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Alice V. Kleeva, Grid for this sequence

Alice V. Kleeva, Illustration of initial terms

Robert Munafo, Sequence A169720, and two others by Alice V. Kleeva

Robert Munafo, Sequence A169720, and two others by Alice V. Kleeva [Cached copy, in pdf format, included with permission]

Index entries for linear recurrences with constant coefficients, signature (7,-14,8).

Formula

a(n) = A033484(n)^2.

G.f.: (1+9*x+2*x^2)/(1-7*x+14*x^2-8*x^3). - Bruno Berselli, Dec 04 2012

a(n) = 7*a(n-1)-14*a(n-2)+8*a(n-3). - Vincenzo Librandi, Dec 04 2012

Mathematica

Table[(2(3*2^(n-1)-1))^2, {n, 0, 30}] (* Harvey P. Dale, Oct 29 2012 *)
CoefficientList[Series[(1+x)/((1-x)*(1-2*x)), {x, 0, 30}], x]^2 (* Vincenzo Librandi, Dec 04 2012 *)

Prog

(Magma) I:=[1, 16, 100]; [n le 3 select I[n] else 7*Self(n-1)-14*Self(n-2)+8*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Dec 04 2012

Crossrefs

Cf. A169720-A169727.

Sequence in context: A001249 A014796 A052206 * A125326 A126484 A091100

Adjacent sequences: A169718 A169719 A169720 * A169722 A169723 A169724

Keyword

nonn,easy

Author

Alice V. Kleeva (alice27353(AT)gmail.com), Jan 19 2010

Status

approved