This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A064072 #24 Feb 16 2025 08:32:45 %S A064072 8,904,355688,296327464,423645846728,925434038426824, %T A064072 2866986638191472168,11956421282992330042984, %U A064072 64584221654333725499376008,438640634423372575622395751944,3658596185733807024739320857622248,36763878323837308563984663576886049704 %N A064072 Generalized tangent number d(7,n). %H A064072 Lars Blomberg, <a href="/A064072/b064072.txt">Table of n, a(n) for n = 1..180</a> %H A064072 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 663-688. %H A064072 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 A064072 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TangentNumber.html">Tangent Number</a>. %F A064072 a(n) = (2*n-1)!*[x^(2*n-1)](sec(7*x)*(-sin(2*x) + sin(4*x) + sin(6*x))). - _Peter Luschny_, Nov 21 2021 %p A064072 egf := sec(7*x)*(-sin(2*x) + sin(4*x) + sin(6*x)): ser := series(egf, x, 24): %p A064072 seq((2*n-1)!*coeff(ser, x, 2*n-1), n = 1..10); # _Peter Luschny_, Nov 21 2021 %Y A064072 Cf. A064068, A349266, A349264. %K A064072 nonn,easy %O A064072 1,1 %A A064072 _Eric W. Weisstein_, Aug 31 2001 %E A064072 Offset changed to 1 by _Lars Blomberg_, Sep 07 2015