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 A381223 #11 Feb 20 2025 23:47:59 %S A381223 2,3,4,6,10,14,18,24,26,30,34,36,42,44,45,46,50,52,54,56,58,60,66,72, %T A381223 76,78,84,90,96,100,102,108,110,112,114,120,122,124,126,130,136,138, %U A381223 144,150,156,160,162,168,170,172,174,176,180,186,188,190,192 %N A381223 Take the list (A381222) of successive values of the smallest number missing from A381019, and keep just the first of any run of successive equal terms. %C A381223 All terms except 2 and 3 are composite numbers, although it is not obvious which composite numbers appear. %H A381223 Michael De Vlieger, <a href="/A381223/b381223.txt">Table of n, a(n) for n = 1..128</a> %e A381223 A381222 begins 2, 3, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 10, 10, 10, ... and discarding terms which have already been seen we get 2, 3, 4, 6, 10, ... %Y A381223 Cf. A381019, A381222. %K A381223 nonn %O A381223 1,1 %A A381223 _N. J. A. Sloane_, Feb 20 2025