OFFSET
1,2
COMMENTS
A007318 * [1, 11, 11, 11, ...].
The binomial transform of [1, c, c, c, ...] has the terms a(n) = 1 - c + c*2^(n-1) if the offset 1 is chosen. The o.g.f. of the a(n) is x*(1+(c-2)*x)/((2x-1)*(x-1)). This applies to A139634 with c=10, to A139635 with c=11, to A139697 with c=12, to A139698 with c=25 and to A099003, A139700, A139701 accordingly. - R. J. Mathar, May 11 2008
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
a(n) = 11*2^(n-1) - 10. - Emeric Deutsch, May 03 2008
a(n) = 2*a(n-1) + 10, with n > 1, a(1)=1. - Vincenzo Librandi, Nov 24 2010
From Colin Barker, Mar 11 2014: (Start)
a(n) = 3*a(n-1) - 2*a(n-2).
G.f.: x*(9*x+1) / ((x-1)*(2*x-1)). (End)
EXAMPLE
a(4) = 78 = (1, 3, 3, 1) dot (1, 11, 11, 11) = (1 + 33 + 33 + 11).
MAPLE
seq(11*2^(n-1)-10, n=1.. 25); # Emeric Deutsch, May 03 2008
MATHEMATICA
a=1; lst={a}; k=11; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 17 2008 *)
CoefficientList[Series[(9 x + 1)/((x - 1) (2 x - 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Mar 13 2014 *)
LinearRecurrence[{3, -2}, {1, 12}, 40] (* Harvey P. Dale, Oct 26 2015 *)
PROG
(PARI) Vec(x*(9*x+1)/((x-1)*(2*x-1)) + O(x^100)) \\ Colin Barker, Mar 11 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Apr 29 2008
EXTENSIONS
More terms from Emeric Deutsch, May 03 2008
More terms from Colin Barker, Mar 11 2014
STATUS
approved