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 A184593 #11 Feb 27 2015 23:26:37
%S A184593 3,5,5,3,7,9,7,3,5,1,5,3,7,9,7,9,5,9,7,11,13,9,11,7,5,9,11,9,5,7,5,9,
%T A184593 7,3,-1,3,1,3,1,3,-1,3,7,9,7,3,7,9,7,3,5,1,5,9,7,9,5,9,7,11,13,15,13,
%U A184593 17,19,17,21,19,17,13,15,11,9,11,7,9,5,3,7,3
%N A184593 5n - A101306: sum_{i=1..n} the last digit of prime(i).
%C A184593 The differences are always odd since the parity of A101306 and n are always opposite.
%C A184593 Positions where a(n)=2k-1 for k>0; 10, 1, 2, 5, 6, 20, 21, 62, 64, 65, 67, 198, 761, 765, 764, 800, ... - _Robert G. Wilson v_, Jun 06 2012
%F A184593 a(n) = 5*n - Sum_{i=1..n} Prime(i) (mod 10).
%t A184593 f[n_] := 5n - Sum[ Mod[ Prime@ k, 10], {k, n}]; Array[f, 80]
%t A184593 Rest@ FoldList[# + 5 - Mod[Prime@ #2, 10] &, 0, Range@ 80]
%Y A184593 Cf. A101306, A122754, A184594.
%K A184593 base,easy,sign
%O A184593 1,1
%A A184593 _Robert G. Wilson v_, Jan 17 2011