A348141 a(n) is the denominator of tan(n * arctan(1/n)).

1, 3, 9, 161, 475, 27755, 60319, 9722113, 13913289, 5707904499, 5061910249, 5039646554593, 2665025213747, 6237995487261915, 1915304790146175, 10303367499652761601, 1801181048868783377, 21891769059478538933603, 2146451844926024801801, 58162468900440912135124001

Offset: 1

Author

Amiram Eldar, Oct 02 2021

Keywords

• nonn
• frac

Links

• Amiram Eldar, Table of n, a(n) for n = 1..387

Crossrefs

Cf. A348131, A348132, A348140 (numerators).

Programs

Mathematica

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