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 A161626 #6 May 04 2019 21:49:45 %S A161626 3,3,5,7,30,36,75,85,140,264,286,450,561,595,722,966,1242,1296,1612, %T A161626 1815,1881,2257,2496,2924,3577,3876,3978,4293,4399,4730,6298,6693, %U A161626 7373,7519,8829,8991,9775,10591,11102,11970,12870,13068,14766,14980,15587,15805 %N A161626 Sum of all numbers from 2*n-1 up to prime(n). %F A161626 a(n) = A000217(A000040(n)) - A000217(2*n-2). %e A161626 a(1) = 1+2 = 3; %e A161626 a(2) = 3; %e A161626 a(3) = 5; %e A161626 a(5) = 9+10+11 = 30. %p A161626 A000217 := proc(n) n*(n+1) /2 ; end: %p A161626 A161626 := proc(n) A000217(ithprime(n))-A000217(2*n-2) ; end: seq(A161626(n),n=1..120) ; # _R. J. Mathar_, Oct 02 2009 %Y A161626 Cf. A000027, A000040, A161570. %K A161626 nonn,easy %O A161626 1,1 %A A161626 _Juri-Stepan Gerasimov_, Jun 15 2009 %E A161626 Edited and corrected by _R. J. Mathar_, Oct 02 2009 %E A161626 Inserted a zero in an A-number - _R. J. Mathar_, Oct 23 2009