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 A333356 #13 Mar 25 2020 07:56:35 %S A333356 11,21,41,54,61,84,96,101,118,124,139,146,151,160,171,181,191,208,211, %T A333356 234,241,269,271,284,296,301,321,331,346,350,361,381,391,408,411,421, %U A333356 439,441,460,478,491,501,534,554,561,586,599,621,648,654,679,686,700,711,741,771,794,806,830,856,861,888 %N A333356 Terms describing the nonprime digits' positions in the way explained in the Comments section. %C A333356 "11" must be read: "At position 1, there is a 1". And indeed, there is, when considering the sequence as a string of concatenated digits; %C A333356 "21" reads: "At position 2, there is a 1" - which is true; %C A333356 "41" reads: "At position 4, there is a 1" - which is also true; %C A333356 "54" reads: "At position 5, there is a 4" - which is also true; %C A333356 ... %C A333356 "101" reads: "At position 10, there is a 1" - which is true (the 1 in 61); etc. %C A333356 We don't read the 2 of 21 as this 2 is a prime digit. Thus 32 and 75 are not in the sequence. %H A333356 Carole Dubois, <a href="/A333356/b333356.txt">Table of n, a(n) for n = 1..2322</a> %Y A333356 Cf. A333234 (nonprimes describing the nonprime digits' positions), A264646 (n concatenated with the n-th digit of S). %K A333356 base,nonn %O A333356 1,1 %A A333356 _Carole Dubois_ and _Eric Angelini_, Mar 15 2020