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 A164740 #11 Feb 17 2019 08:50:59
%S A164740 0,1,5,17,185,629,7709,27593,364721,18512789,69273665,3714566309,
%T A164740 53634713549,204560302841,2994414645857,169947155749829,
%U A164740 9770521225481753,37800705069076949,2202596307308603177
%N A164740 (2^p-(p+2))/p as p runs through the primes.
%F A164740 a(n) = 2*A007663(n)-1. [_T. D. Noe_, Aug 24 2009]
%t A164740 f[n_] := Block[{p = Prime@n}, (2^p - p - 2)/p]; Array[f, 15]
%t A164740 Table[(2^p-p-2)/p,{p,Prime[Range[20]]}] (* _Harvey P. Dale_, Aug 15 2017 *)
%K A164740 nonn
%O A164740 1,3
%A A164740 Tanin (Mirza Sabbir Hossain Beg) (mirzasabbirhossainbeg(AT)yahoo.com), Aug 24 2009
%E A164740 Edited by _N. J. A. Sloane_, Aug 24 2009
%E A164740 Extended and offset changed by _T. D. Noe_ and _Robert G. Wilson v_, Aug 24 2009