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 A115606 #4 Mar 30 2012 18:40:36 %S A115606 0,43,104,177,256,353,456,607,770,943,1136,1359,1588,1829,2100,2377, %T A115606 2660,2973,3304,3653,4020,4393,4776,5173,5594,6027,6466,6923,7386, %U A115606 7909,8456,9049,9650,10257,10870,11489,12132,12793,13466,14157,14866,15593 %N A115606 Partial sums of A102540 (primes that are not Chen primes). %C A115606 See also A109611 (Chen primes: primes p such that p + 2 is either a prime or a semiprime), A102540 (primes that are not Chen primes). a(n) is prime for a(1) = 43, a(5) = 353 [Chen prime], a(7) = 607, a(15) = 2377, a(31) = 9049, a(35) = 11489 [Chen prime], a(49) = 22013. a(n) is semiprime for a(3) = 177, a(9) = 943, a(13) = 1829, a(17) = 2973, a(19) = 3653, a(21) = 4393, a(23) = 5173, a(24) = 5594, a(29) = 7909, a(37) = 12793, a(38) = 13466, a(40) = 14866, a(41) = 15593, a(43) = 17065, a(45) = 18595. %F A115606 a(n) = SUM[k=1..n] A102540(k). %e A115606 a(5) = 43 + 61 + 73 + 79 + 97 = 353, which happens to be the Chen prime A109611(52). %Y A115606 Cf. A000040, A001358, A007504, A102540, A109611. %K A115606 easy,nonn %O A115606 0,2 %A A115606 _Jonathan Vos Post_, Mar 09 2006