A180418 - OEIS

%I #16 Mar 01 2024 08:46:33

%S 1,3,39,32163,1720635,12345020175,1530993953307,44148864630732711,

%T 797213247855503373843915,281095572810489332134542303,

%U 26242778669866462496740532647355475

%N a(n) = ( A000111(p) -(-1)^((p-1)/2) )/p, where p = prime(n).

%H Amiram Eldar, <a href="/A180418/b180418.txt">Table of n, a(n) for n = 2..92</a>

%F a(n) = ( A000111(A000040(n)) -A070750(n) )/A000040(n). - _R. J. Mathar_, Sep 19 2010

%t 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 Cf. A000040, A000111, A070750.

%K nonn

%O 2,2

%A _Vladimir Shevelev_, Sep 03 2010

%E Extended by _R. J. Mathar_, Sep 19 2010

%E a(8) onwards from _Robert G. Wilson v_, Sep 04 2010