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A014833 2^n - n(n+1)/2. 2
1, 1, 1, 2, 6, 17, 43, 100, 220, 467, 969, 1982, 4018, 8101, 16279, 32648, 65400, 130919, 261973, 524098, 1048366, 2096921, 4194051, 8388332, 16776916, 33554107, 67108513, 134217350, 268435050, 536870477 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..240

Index entries for linear recurrences with constant coefficients, signature (5, -9, 7, -2).

FORMULA

From Harvey P. Dale, May 12 2011: (Start)

a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4); a(0)=1, a(1)=1, a(2)=1, a(3)=2.

G.f.: 1/(1-2*x) + 1/(-1+x)^3 + 1/(-1+x)^2. (End)

MAPLE

seq((2^n-n^2+n)/2, n=1..30); # Zerinvary Lajos, Jul 01 2007

MATHEMATICA

Table[2^n-n (n+1)/2, {n, 0, 50}] (* or *) LinearRecurrence[{5, -9, 7, -2}, {1, 1, 1, 2}, 50] (* Harvey P. Dale, May 12 2011 *)

PROG

(MAGMA) [2^n - n*(n+1)/2: n in [0..50]]; // Vincenzo Librandi, Apr 25 2011

CROSSREFS

Sequence in context: A252814 A072077 A229732 * A130104 A019439 A018024

Adjacent sequences:  A014830 A014831 A014832 * A014834 A014835 A014836

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified March 19 11:10 EDT 2019. Contains 321329 sequences. (Running on oeis4.)