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 A003311 M2436 #26 Jul 30 2025 02:00:37 %S A003311 3,5,8,11,15,18,23,27,32,38,42,47,53,57,63,71,75,78,90,93,98,105,113, %T A003311 117,123,132,137,140,147,161,165,168,176,183,188,197,206,212,215,227, %U A003311 233,237,243,252,258,267,278,282,287,293,303,312,317,323 %N A003311 Write down the numbers from 3 to infinity. Take next number, M say, that has not been crossed off. Counting through the numbers that have not yet been crossed off after that M, cross off the first, (M+1)st, (2M+1)st, (3M+1)st, etc. Repeat. The numbers that are left form the sequence. %D A003311 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A003311 Reinhard Zumkeller, <a href="/A003311/b003311.txt">Table of n, a(n) for n = 1..10000</a> %H A003311 Popular Computing (Calabasas, CA), <a href="/A003309/a003309.pdf">Sieves: Problem 43</a>, Vol. 2 (No. 13, Apr 1974), pp. 6-7. Based on a misreading of Sieve #3. A100464 is the correct version. [Annotated and scanned copy] %H A003311 <a href="/index/Si#sieve">Index entries for sequences generated by sieves</a> %e A003311 The first few sieving stages are as follows: %e A003311 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ... %e A003311 3 X 5 6 X 8 9 XX 11 12 XX 14 15 XX 17 18 XX 20 ... %e A003311 3 X 5 X X 8 9 XX 11 12 XX XX 15 XX 17 18 XX 20 ... %e A003311 3 X 5 X X 8 X XX 11 12 XX XX 15 XX 17 18 XX 20 ... %e A003311 3 X 5 X X 8 X XX 11 XX XX XX 15 XX 17 18 XX 20 ... %e A003311 3 X 5 X X 8 X XX 11 XX XX XX 15 XX XX 18 XX 20 ... %o A003311 (Haskell) %o A003311 a003311 n = a003311_list !! (n-1) %o A003311 a003311_list = f [3..] where %o A003311 f (x:xs) = x : f (g xs) where %o A003311 g zs = us ++ g vs where (_:us, vs) = splitAt x zs %o A003311 -- _Reinhard Zumkeller_, Nov 12 2014 %Y A003311 Cf. A003309, A003310, A100464, A003312, A100562, A100585, A052548. %K A003311 nonn %O A003311 1,1 %A A003311 _N. J. A. Sloane_ %E A003311 Entry revised Nov 29 2004