A164559 a(n) = 6^n/3 - 1.

1, 11, 71, 431, 2591, 15551, 93311, 559871, 3359231, 20155391, 120932351, 725594111, 4353564671, 26121388031, 156728328191, 940369969151, 5642219814911, 33853318889471, 203119913336831, 1218719480020991, 7312316880125951, 43873901280755711, 263243407684534271

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..600

Index entries for linear recurrences with constant coefficients, signature (7,-6).

Formula

a(n) = 6*a(n-1)+5 for n > 2; a(1) = 1, a(2) = 11.

G.f.: x*(1+4*x)/((1-x)*(1-6*x)).

Prog

(Magma) [ 6^n/3-1: n in [1..20] ];

Crossrefs

Cf. A000400 (powers of 6), A024062 (6^n-1), A164560.

Sequence in context: A268985 A211386 A049350 * A319535 A300541 A123362

Adjacent sequences: A164556 A164557 A164558 * A164560 A164561 A164562

Keyword

nonn,easy,changed

Author

Klaus Brockhaus, Aug 16 2009

Status

approved