|
%I #20 Nov 22 2021 02:36:10
%S 12,2160,1415232,1951153920,4611775398912,16653520425185280,
%T 85285640517460180992,587950108643300554506240,
%U 5249943672359370392053481472,58942155612887708094647422156800,812681867463337890406273965833060352,13499458606943117379769406368204676136960
%N Generalized tangent number d(9,n).
%H Lars Blomberg, <a href="/A064074/b064074.txt">Table of n, a(n) for n = 1..174</a>
%H D. Shanks, <a href="http://dx.doi.org/10.1090/S0025-5718-1967-0223295-5">Generalized Euler and class numbers</a>. Math. Comp. 21 (1967) 689-694.
%H D. Shanks, <a href="http://dx.doi.org/10.1090/S0025-5718-1968-0227093-9">Corrigenda to: "Generalized Euler and class numbers"</a>, Math. Comp. 22 (1968), 699.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TangentNumber.html">Tangent Number</a>.
%F a(n) = (2*n-1)!*[x^(2*n-1)](sec(9*x)*4*sin(3*x)*cos(3*x)^2). - _Peter Luschny_, Nov 21 2021
%p egf := sec(9*x)*4*sin(3*x)*cos(3*x)^2: ser := series(egf, x, 24):
%p seq((2*n-1)!*coeff(ser, x, 2*n-1), n = 1..10); # _Peter Luschny_, Nov 21 2021
%Y Cf. A064070, A349268, A349264.
%K nonn,easy
%O 1,1
%A _Eric W. Weisstein_, Aug 31 2001
%E Offset changed to 1 by _Lars Blomberg_, Sep 07 2015
| 