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A060188 A column and  diagonal of A060187. 7
1, 6, 23, 76, 237, 722, 2179, 6552, 19673, 59038, 177135, 531428, 1594309, 4782954, 14348891, 43046704, 129140145, 387420470, 1162261447, 3486784380, 10460353181, 31381059586, 94143178803, 282429536456, 847288609417 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

Sums of rows of the numerators and of the denominators of the redundant Stern-Brocot structure A152975/A152976: a(n+2) = Sum(A152975(k):2^n<=k<2^(n+1)) = Sum(A152976(k):2^n<=k<2^(n+1)). - Reinhard Zumkeller, Dec 22 2008

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 2..2000

P. A. MacMahon, The divisors of numbers, Proc. London Math. Soc., (2) 19 (1920), 305-340; Coll. Papers II, pp. 267-302.

Index entries for linear recurrences with constant coefficients, signature (5,-7,3).

FORMULA

a(n) =3^(n-1)-n =A061980(n-1, 2). - Henry Bottomley, May 24 2001

With offset 0, this is 3^(n+1)-n-2. Partial sums of A048473. - Paul Barry, Jun 24 2003

a(n) = 5*a(n-1)-7*a(n-2)+3*a(n-3). G.f.: -x^2*(x+1) / ((x-1)^2*(3*x-1)). - Colin Barker, Dec 19 2012

E.g.f.: (exp(3*x) - 3*x*exp(x) - 1)/3. - Wolfdieter Lang, Apr 17 2017

MAPLE

a[0]:=1:for n from 1 to 24 do a[n]:=(4*a[n-1]-3*a[n-2]+2) od: seq(a[n], n=0..24); # Zerinvary Lajos, Jun 08 2007

MATHEMATICA

s=1; lst={s}; Do[s+=(n+=s++)+n; AppendTo[lst, s], {n, 1, 5!, 1}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 15 2008 *)

PROG

(MAGMA) [3^(n-1)-n: n in [2..30]]; // Vincenzo Librandi, Sep 05 2011

CROSSREFS

Cf. A048473, A060187 (first differences).

Sequence in context: A136530 A259033 A054459 * A058751 A034359 A220148

Adjacent sequences:  A060185 A060186 A060187 * A060189 A060190 A060191

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Mar 20 2001

EXTENSIONS

More terms from Vladeta Jovovic, Mar 20 2001

STATUS

approved

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Last modified October 23 14:37 EDT 2018. Contains 316528 sequences. (Running on oeis4.)