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 A180418 #16 Mar 01 2024 08:46:33
%S A180418 1,3,39,32163,1720635,12345020175,1530993953307,44148864630732711,
%T A180418 797213247855503373843915,281095572810489332134542303,
%U A180418 26242778669866462496740532647355475
%N A180418 a(n) = ( A000111(p) -(-1)^((p-1)/2) )/p, where p = prime(n).
%H A180418 Amiram Eldar, <a href="/A180418/b180418.txt">Table of n, a(n) for n = 2..92</a>
%F A180418 a(n) = ( A000111(A000040(n)) -A070750(n) )/A000040(n). - _R. J. Mathar_, Sep 19 2010
%t A180418 t = Range[0, 60]! CoefficientList[Series[Sec@x + Tan@x, {x, 0, 60}], x]; f[n_] := (Rest[t][[Prime@n]] - (-1)^((Prime@n - 1)/2))/Prime@n; Array[f, 11, 2] (* _Robert G. Wilson v_, Sep 04 2010 *)
%Y A180418 Cf. A000040, A000111, A070750.
%K A180418 nonn
%O A180418 2,2
%A A180418 _Vladimir Shevelev_, Sep 03 2010
%E A180418 Extended by _R. J. Mathar_, Sep 19 2010
%E A180418 a(8) onwards from _Robert G. Wilson v_, Sep 04 2010