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 A080476 Floor( geometric mean of next n numbers ). 3

%I

%S 1,2,4,8,12,18,24,32,40,50,60,72,84,98,112,128,144,162,180,200,220,

%T 242,264,288,312,338,364,392,420,450,480,512,544,578,612,648,684,722,

%U 760,800,840,882,924,968,1012,1058,1104,1152,1200,1250,1300,1352,1404,1458

%N Floor( geometric mean of next n numbers ).

%C Essentially the same as A007590: a(n) = A007590(n) for n>=2.

%C Also, floor( harmonic mean of next n numbers ).

%C Also, floor(sqrt(A131479(n)+1)). - _Richard R. Forberg_, Aug 04 2013

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,1).

%F a(n+3) = 2*a(n+2)-a(n+1) if n even, a(n+3) = 2*a(n+2)-a(n+1)+2 if n odd, with a(1)=1, a(2)=2, a(3)=4 - _Yosu Yurramendi_, Sep 12 2008

%F a(n)= 2*a(n-1)-2*a(n-3)+a(n-4) for n>5. G.f.: x*(x^4-2*x^3-1) / ((x-1)^3*(x+1)). - _Colin Barker_, Aug 08 2013

%e a(4) = floor( (7*8*9*10)^(1/4) ) = 8.

%e a(4) = floor( 1/{ (1/7 + 1/8 + 1/9 + 1/10 )*(1/4)} ) = 8.

%o (PARI) a(n)=if(n<2,n>0,n^2\2);

%Y Cf. A000982.

%K nonn,easy

%O 1,2

%A _Amarnath Murthy_, Mar 11 2003

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003

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Last modified July 23 20:56 EDT 2019. Contains 325265 sequences. (Running on oeis4.)