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 A044236 #11 Sep 03 2025 09:38:17 %S A044236 49,113,177,241,305,369,392,433,497,561,625,689,753,817,881,904,945, %T A044236 1009,1073,1137,1201,1265,1329,1393,1416,1457,1521,1585,1649,1713, %U A044236 1777,1841,1905,1928,1969,2033,2097,2161,2225,2289,2353 %N A044236 Numbers k such that string 6,1 occurs in the base 8 representation of k but not of k-1. %H A044236 Paolo Xausa, <a href="/A044236/b044236.txt">Table of n, a(n) for n = 1..10000</a> %t A044236 A044236Q[k_] := StringContainsQ[IntegerString[k, 8], "61"] && StringFreeQ[IntegerString[k - 1, 8], "61"]; %t A044236 Select[Range[5000], A044236Q] (* _Paolo Xausa_, Sep 03 2025 *) %Y A044236 Cf. A007094. %K A044236 nonn,base,changed %O A044236 1,1 %A A044236 _Clark Kimberling_