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 A284923 #10 Aug 06 2025 16:30:56
%S A284923 2,9,22,29,92,99,222,229,292,299,922,929,992,999,2222,2229,2292,2299,
%T A284923 2922,2929,2992,2999,9222,9229,9292,9299,9922,9929,9992,9999,22222,
%U A284923 22229,22292,22299,22922,22929,22992,22999,29222,29229,29292,29299,29922,29929
%N A284923 Numbers with digits 2 and 9 only.
%t A284923 Select[Range[30000],SubsetQ[{2,9},Sort[DeleteDuplicates[IntegerDigits[#]]]] &] (* _Stefano Spezia_, Aug 06 2025 *)
%o A284923 (Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {2, 9}]
%Y A284923 Prime terms are in A020460.
%Y A284923 Numbers with digits 2 and k only for k = 0 - 1 and 3 - 9: A169965 (k = 0), A007931 (k = 1), A032810 (k = 3), A284920 (k = 4), A072961 (k = 5), A284632 (k = 6), A284921 (k = 7), A284922 (k = 8), this sequence (k = 9).
%K A284923 nonn,base
%O A284923 1,1
%A A284923 _Jaroslav Krizek_, Apr 06 2017