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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; internal format)
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OFFSET
| 2,2
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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)). [From Reinhard Zumkeller, Dec 22 2008]
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REFERENCES
| P. A. MacMahon, The divisors of numbers, Proc. London Math. Soc., (2) 19 (1920), 305-340; Coll. Papers II, pp. 267-302.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 2..2000
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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
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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 (zerinvarylajos(AT)yahoo.com), Jun 08 2007
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MATHEMATICA
| s=1; lst={s}; Do[s+=(n+=s++)+n; AppendTo[lst, s], {n, 1, 5!, 1}]; lst [From Vladimir Orlovsky, Nov 15 2008]
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PROG
| (MAGMA) [3^(n-1)-n: n in [2..30]]; // Vincenzo Librandi, Sep 05 2011
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CROSSREFS
| Sequence in context: A038797 A136530 A054459 * A058751 A034359 A114245
Adjacent sequences: A060185 A060186 A060187 * A060189 A060190 A060191
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mar 20 2001
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 20 2001
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