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 A135495 #17 Sep 10 2024 18:42:55 %S A135495 0,121648,121684,124168,124816,128164,128416,161248,161284,164128, %T A135495 164812,168124,168412,412168,412816,416128,416812,481216,481612, %U A135495 812164,812416,816124,816412,841216,841612,1121648,1121684,1124168 %N A135495 Numbers n with property that for each single digit d of n, we can also see the decimal expansion of 2d as a substring of n. %H A135495 David Applegate, <a href="/A135495/b135495.txt">Table of n, a(n) for n = 1..301</a> %t A135495 Select[Range[0, 10^6], Function[d, AllTrue[IntegerDigits[2 d], SequenceCount[d, #] >= 1 &]]@ IntegerDigits[#] &] (* _Michael De Vlieger_, Jan 11 2018 *) %o A135495 (C++) // See the Applegate link in A135463. %Y A135495 Cf. A135463, A134962. %K A135495 nonn,base %O A135495 1,2 %A A135495 _Zak Seidov_, Feb 08 2008 %E A135495 Corrected by _David Applegate_, Feb 09 2008