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A195458 a(n) = floor(sqrt(n) * a(n-1)), starting with 1. 1

%I

%S 1,1,1,2,4,8,16,32,96,288,864,2592,7776,23328,69984,279936,1119744,

%T 4478976,17915904,71663616,286654464,1146617856,4586471424,

%U 18345885696,91729428480,458647142400,2293235712000,11466178560000,57330892800000,286654464000000

%N a(n) = floor(sqrt(n) * a(n-1)), starting with 1.

%C a(n) = r(n+2)/sqrt(2); r(1) = sqrt(2); r(n) = r(n-1)/sqrt(n-1) if r(n-1) is a square else r(n) = r(n-1)*floor(sqrt(n-1).

%C A variation of Recamán's A008336.

%p r := proc(n) option remember; if n = 1 then sqrt(2)

%p elif type(r(n-1),square) then r(n-1)/sqrt(n-1)

%p else r(n-1)*floor(sqrt(n-1)) fi end:

%p A195458 := proc(n) r(n+2)/sqrt(2) end:

%t a[1] = 1;

%t a[n_] := a[n] = Floor[Sqrt[n]] a[n - 1]

%t Table[a[n], {n, 20}] (* _David Callan_, Aug 14 2013 *)

%Y Cf. A008336.

%K nonn

%O 1,4

%A _Peter Luschny_, Sep 18 2011

%E Better name from _David Callan_, Aug 14 2013

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Last modified August 7 16:00 EDT 2022. Contains 355994 sequences. (Running on oeis4.)