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A036799 a(n) = 2 + 2^(n+1)*(n-1). 20
0, 2, 10, 34, 98, 258, 642, 1538, 3586, 8194, 18434, 40962, 90114, 196610, 425986, 917506, 1966082, 4194306, 8912898, 18874370, 39845890, 83886082, 176160770, 369098754, 771751938, 1610612738, 3355443202, 6979321858, 14495514626, 30064771074, 62277025794 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
This sequence is a part of a class of sequences of the type: a(n) = Sum_{i=0..n} (C^i)*(i^k). This sequence has C=2, k=1. Sequence A036800 has C=2, k=2. Suppose C >= 2, k >= 1 are integers. What is the general closed form for a(n)? - Ctibor O. Zizka, Feb 07 2008
Partial sums of A036289. - Vladimir Joseph Stephan Orlovsky, Jul 09 2011
a(n) is the number of swaps needed in the worst case, when successively inserting 2^(n+1) - 1 keys into an initially empty binary heap (thus creating a tree with n+1 full levels). - Rudy van Vliet, Nov 09 2015
a(n) is also the total path length of the complete binary tree of height n, with nodes at depths 0,...,n. Total path length is defined to be the sum of depths over all nodes. - F. Skerman, Jul 02 2017
For n >= 1, every number greater than or equal to a(n-1) can be written as a sum of (not necessarily distinct) numbers of the form 2^n - 2^k with 0 <= k < n. However, a(n-1) - 1 cannot be written in this way. See problem N1 from the 2014 International Mathematics Olympiad Shortlist. - Dylan Nelson, Jun 02 2023
REFERENCES
M. Petkovsek et al., A=B, Peters, 1996, p. 97.
LINKS
R. K. Guy, Catwalks, sandsteps and Pascal pyramids, J. Integer Sequences, Vol. 3 (2000), Article #00.1.6.
Jia Huang, Partially Palindromic Compositions, J. Int. Seq. (2023) Vol. 26, Art. 23.4.1. See pp. 3, 4, 9.
Problem Selection Committee for the 2014 IMO, Shortlisted Problems with Solutions for the 55th International Mathematical Olympiad. See pp. 9, 68-70.
Stanislav Sykora, Finite and Infinite Sums of the Power Series (k^p)(x^k), DOI 10.3247/SL1Math06.002, Section V.
FORMULA
a(n) = (n-1) * 2^(n+1) + 2.
a(n) = 2 * A000337(n).
a(n) = Sum_{k=1..n} k*2^k. - Benoit Cloitre, Oct 25 2002
G.f.: 2*x/((1-x)*(1-2*x)^2). - Colin Barker, Apr 30 2012
a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3) for n > 2. - Wesley Ivan Hurt, Nov 12 2015
a(n) = Sum_{k=0..n} Sum_{i=0..n} k * binomial(k,i). - Wesley Ivan Hurt, Sep 21 2017
E.g.f.: 2*exp(x) - 2*(1-2*x)*exp(2*x). - G. C. Greubel, Mar 29 2021
MAPLE
A036799:=n->2+2^(n+1)*(n-1): seq(A036799(n), n=0..40); # Wesley Ivan Hurt, Nov 12 2015
MATHEMATICA
Accumulate[Table[n*2^n, {n, 0, 40}]] (* Vladimir Joseph Stephan Orlovsky, Jul 09 2011 *)
PROG
(Haskell) a036799 n = (n-1)*2^(n+1) + 2 -- Reinhard Zumkeller, May 24 2012
(PARI) a(n)=2+(n-1)<<(n+1) \\ Charles R Greathouse IV, Sep 28 2015
(PARI) concat(0, Vec(2*x/((1-x)*(1-2*x)^2) + O(x^40))) \\ Altug Alkan, Nov 09 2015
(Magma) [2+2^(n+1)*(n-1) : n in [0..40]]; // Wesley Ivan Hurt, Nov 12 2015
(Sage) [2^(n+1)*(n-1) +2 for n in (0..40)] # G. C. Greubel, Mar 29 2021
CROSSREFS
Sequence in context: A304159 A211905 A022498 * A190161 A196969 A351551
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified May 19 04:28 EDT 2024. Contains 372666 sequences. (Running on oeis4.)