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A026622 a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A026615. 4
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 (list; graph; refs; listen; history; text; internal format)
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 A198896 A026688

Adjacent sequences:  A026619 A026620 A026621 * A026623 A026624 A026625

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 17 23:07 EDT 2022. Contains 353779 sequences. (Running on oeis4.)