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 A172188 #9 Nov 21 2013 12:49:59 %S A172188 2,7,18,35,58,87,128,175,228,287,358,441,530,631,738,851,982,1119, %T A172188 1268,1435,1608,1787,1978,2175,2402,2635,2874,3125,3382,3645,3914, %U A172188 4195,4488,4799,5116,5463,5816,6175,6558,6947,7348,7767,8198,8641,9090,9551,10018 %N A172188 Partial sums of primes of the form 3*k-1. %e A172188 a(1)=3*1-1=2, a(2)=2+3*2-1=7. %p A172188 Contribution from _R. J. Mathar_, Apr 24 2010: (Start) %p A172188 A003627 := proc(n) if n <= 2 then op(n,[2,5]) ; else for a from procname(n-1)+2 by 2 do if isprime(a) and (a mod 3) =2 then return a ; end if; end do: end if; end proc: %p A172188 A172188 := proc(n) add( A003627(i),i=1..n) ; end proc: seq(A172188(n),n=1..80) ; (End) %t A172188 Accumulate[Select[Prime[Range[100]],IntegerQ[(#+1)/3]&]] (* _Harvey P. Dale_, Apr 04 2011 *) %Y A172188 Cf. A038361. %K A172188 nonn %O A172188 1,1 %A A172188 _Juri-Stepan Gerasimov_, Jan 29 2010, Feb 01 2010 %E A172188 Entries checked by _R. J. Mathar_, Apr 24 2010