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 A033160 #19 Jul 08 2025 19:42:47
%S A033160 2,4,5,7,11,13,14,16,29,31,32,34,38,40,41,43,83,85,86,88,92,94,95,97,
%T A033160 110,112,113,115,119,121,122,124,245,247,248,250,254,256,257,259,272,
%U A033160 274,275,277,281,283,284,286,326,328,329,331,335,337,338,340,353,355,356,358,362
%N A033160 Begins with (2, 4); avoids 3-term arithmetic progressions.
%H A033160 F. Iacobescu, <a href="http://fs.unm.edu/SN/SPartitionType.pdf">Smarandache Partition Type and Other Sequences</a>, Bull. Pure Appl. Sci. 16E, 237-240, 1997.
%H A033160 H. Ibstedt, <a href="http://vixra.org/abs/1403.0853">A Few Smarandache Sequences</a>, Smarandache Notions Journal, Vol. 8, No. 1-2-3, 1997, 170-183.
%H A033160 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/NonarithmeticProgressionSequence.html">Nonarithmetic Progression Sequence</a>
%t A033160 Select[Range[1000], MatchQ[IntegerDigits[#-2, 3], {(0|1)..., 0|2}]&] (* _Jean-François Alcover_, Jan 13 2019, after _Tanya Khovanova_ in A186776 *)
%Y A033160 a(n) = A186776(n)+2 = A004793(n)+1 = A033163(n)-1. Cf. A185256.
%K A033160 nonn
%O A033160 1,1
%A A033160 _N. J. A. Sloane_