A348141 - OEIS

%I #8 Jan 01 2022 08:15:24

%S 1,3,9,161,475,27755,60319,9722113,13913289,5707904499,5061910249,

%T 5039646554593,2665025213747,6237995487261915,1915304790146175,

%U 10303367499652761601,1801181048868783377,21891769059478538933603,2146451844926024801801,58162468900440912135124001

%N a(n) is the denominator of tan(n * arctan(1/n)).

%H Amiram Eldar, <a href="/A348141/b348141.txt">Table of n, a(n) for n = 1..387</a>

%t f[n_] := Module[{s = 1/n}, Do[s = (s + 1/n)/(1 - s/n), {k, 1, n - 1}]; s]; Denominator @ Array[f, 20]

%Y Cf. A348131, A348132, A348140 (numerators).

%K nonn,frac

%O 1,2

%A _Amiram Eldar_, Oct 02 2021