A026622 a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A026615.

1, 2, 5, 12, 26, 54, 110, 222, 446, 894, 1790, 3582, 7166, 14334, 28670, 57342, 114686, 229374, 458750, 917502, 1835006, 3670014, 7340030, 14680062, 29360126, 58720254, 117440510, 234881022, 469762046, 939524094, 1879048190, 3758096382, 7516192766

Offset

0,2

Links

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-2).

Formula

a(n) = 7 * 2^(n-2) - 2, a(0) = 1, a(1) = 2 (conjectured). Cf. A026624. - Ralf Stephan, Feb 05 2004

a(n) = 2*a(n-1) + 2, n>2. - Gary Detlefs, Jun 22 2010

a(n) = 3*a(n-1)-2*a(n-2) for n>3. G.f.: (1-x+x^2+x^3) / ((1-x)*(1-2*x)). - Colin Barker, Feb 17 2016

Mathematica

a=5; lst={1, 2, a}; k=7; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 16 2008 *)

Prog

(PARI) Vec((1-x+x^2+x^3)/((1-x)*(1-2*x)) + O(x^40)) \\ Colin Barker, Feb 17 2016

Crossrefs

Sequence in context: A193263 A221949 A262803 * A297618 A360785 A198896

Adjacent sequences: A026619 A026620 A026621 * A026623 A026624 A026625

Keyword

nonn,easy

Author

Clark Kimberling

Status

approved