login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Partial sums of floor(4^n/7).
1

%I #35 Sep 08 2022 08:45:54

%S 0,2,11,47,193,778,3118,12480,49929,199725,798911,3195656,12782636,

%T 51130558,204522247,818089003,3272356029,13089424134,52357696554,

%U 209430786236,837723144965,3350892579881,13403570319547,53614281278212,214457125112872

%N Partial sums of floor(4^n/7).

%C Partial sums of A037521.

%H Vincenzo Librandi, <a href="/A178710/b178710.txt">Table of n, a(n) for n = 1..700</a>

%H Mircea Merca, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL14/Merca/merca3.html">Inequalities and Identities Involving Sums of Integer Functions</a> J. Integer Sequences, Vol. 14 (2011), Article 11.9.1.

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4,1,-5,4).

%F a(n) = round((8*4^n - 14*n - 13)/42).

%F a(n) = floor((8*4^n - 14*n - 8)/42).

%F a(n) = ceiling((8*4^n - 14*n - 18)/42).

%F a(n) = round((8*4^n - 14*n - 8)/42).

%F a(n) = a(n-3) + 3*4^(n-2) - 1, n > 3.

%F a(n) = 5*a(n-1) - 4*a(n-2) + a(n-3) - 5*a(n-4) + 4*a(n-5), n > 5.

%F G.f.: x^2*(2+x)/ ( (1-4*x)*(1+x+x^2)*(1-x)^2 ).

%e a(4) = 0 + 2 + 9 + 36 = 47.

%p A178710 := proc(n) add( floor(4^i/7),i=0..n) ; end proc:

%t Accumulate[Floor[4^Range[30]/7]] (* or *) LinearRecurrence[{5,-4,1,-5,4},{0,2,11,47,193},30] (* _Harvey P. Dale_, Aug 15 2015 *)

%o (Magma) [Round((8*4^n-14*n-13)/42): n in [1..30]]; // _Vincenzo Librandi_, Jun 21 2011

%o (PARI) vector(30, n, ((8*4^n-14*n-8)/42)\1) \\ _G. C. Greubel_, Jan 25 2019

%o (Sage) [floor((8*4^n-14*n-8)/42) for n in (1..30)] # _G. C. Greubel_, Jan 25 2019

%Y Cf. A037521.

%K nonn,less

%O 1,2

%A _Mircea Merca_, Dec 26 2010