A164560 Partial sums of A164532.

1, 5, 11, 35, 71, 215, 431, 1295, 2591, 7775, 15551, 46655, 93311, 279935, 559871, 1679615, 3359231, 10077695, 20155391, 60466175, 120932351, 362797055, 725594111, 2176782335, 4353564671, 13060694015, 26121388031, 78364164095

Offset

1,2

Comments

Interleaving of A164559 and A024062 without initial term 0.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..900

Index entries for linear recurrences with constant coefficients, signature (1,6,-6)

Formula

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

a(n) = (3-(-1)^n)*6^(1/4*(2*n-1+(-1)^n))/2-1.

G.f.: x*(1+4*x)/((1-x)*(1-6*x^2)).

Prog

(Magma) T:=[ n le 2 select 3*n-2 else 6*Self(n-2): n in [1..28] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];

Crossrefs

Cf. A164532, A164123 (partial sums of A162436), A164559 (6^n/3-1), A024062 (6^n-1).

a(n) = A026549(n)-1.

Sequence in context: A194589 A189918 A318415 * A054854 A188161 A323352

Adjacent sequences: A164557 A164558 A164559 * A164561 A164562 A164563

Keyword

nonn

Author

Klaus Brockhaus, Aug 16 2009

Status

approved