A180418 a(n) = ( A000111(p) -(-1)^((p-1)/2) )/p, where p = prime(n).

1, 3, 39, 32163, 1720635, 12345020175, 1530993953307, 44148864630732711, 797213247855503373843915, 281095572810489332134542303, 26242778669866462496740532647355475

Offset: 2

Author

Vladimir Shevelev, Sep 03 2010

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 2..92

Crossrefs

Cf. A000040, A000111, A070750.

Programs

Mathematica

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 *)

Formula

a(n) = ( A000111(A000040(n)) -A070750(n) )/A000040(n). - R. J. Mathar, Sep 19 2010

Extensions

Extended by R. J. Mathar, Sep 19 2010

a(8) onwards from Robert G. Wilson v, Sep 04 2010