A099856 Expansion of (1+3x)/(1-3x).

1, 6, 18, 54, 162, 486, 1458, 4374, 13122, 39366, 118098, 354294, 1062882, 3188646, 9565938, 28697814, 86093442, 258280326, 774840978, 2324522934, 6973568802, 20920706406, 62762119218, 188286357654, 564859072962, 1694577218886

Offset

0,2

Comments

A099858 gives a Chebyshev transform. Binomial transform is A083420.

Hankel transform is 1, -18, 0, 0, 0, 0, 0, 0, 0, ... - Philippe Deléham, Dec 13 2011

Links

Table of n, a(n) for n=0..25.

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

Formula

a(n) = 2*3^n - 0^n.

a(n) = A025192(n+1), n>0. - R. J. Mathar, Sep 02 2008

a(n) = Sum_{k=0..n} A093561(n,k)*2^k. - Philippe Deléham, Dec 13 2011

Mathematica

CoefficientList[Series[(1+3x)/(1-3x), {x, 0, 30}], x] (* or *) Join[{1}, NestList[3#&, 6, 30]] (* Harvey P. Dale, Nov 08 2011 *)

Prog

(PARI) Vec((1+3*x)/(1-3*x) + O(x^40)) \\ Michel Marcus, Dec 11 2015

Crossrefs

Sequence in context: A174313 A002933 A016089 * A292295 A183913 A056349

Adjacent sequences: A099853 A099854 A099855 * A099857 A099858 A099859

Keyword

easy,nonn

Author

Paul Barry, Oct 28 2004

Status

approved