A043160 - OEIS

%I #14 Nov 11 2022 14:05:32

%S 11,25,75,88,139,153,200,217,267,281,331,345,395,409,459,473,523,537,

%T 587,600,651,665,704,779,793,843,857,907,921,971,985,1035,1049,1099,

%U 1112,1163,1177,1224,1241,1291,1305,1355,1369,1419,1433,1483,1497,1547,1561

%N Numbers k such that 1 and 3 occur juxtaposed in the base-8 representation of k but not of k-1.

%H Michael S. Branicky, <a href="/A043160/b043160.txt">Table of n, a(n) for n = 1..10000</a>

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{1,3}]>0 || SequenceCount[ IntegerDigits[n,8],{3,1}]>0,1,0],{n,1600}],{0,1}][[All,2]] (* _Harvey P. Dale_, Nov 11 2022 *)

%o (Python)

%o def has13or31(n): o = oct(n); return "13" in o or "31" in o

%o def ok(n): return has13or31(n) and not has13or31(n-1)

%o print([k for k in range(1600) if ok(k)]) # _Michael S. Branicky_, Nov 25 2021

%Y Cf. A007094, A043940.

%K nonn,base

%O 1,1

%A _Clark Kimberling_