cp's OEIS Frontend

A160234 Number of n-digit "early bird numbers" A116700.

%I A160234 #16 Feb 06 2023 15:40:49
%S A160234 0,45,630,6896,73059,757755,7773854,79228098,803943262,8133323510
%N A160234 Number of n-digit "early bird numbers" A116700.
%e A160234 a(1) = 0 because there are no 1-digit terms in A116700;
%e A160234 a(1) = 45 because there are 45 2-digit terms in A116700: 12, 21, 23, 31, 32, 34, 41, 42, 43, 45, 51, 52, 53, 54, 56, 61, 62, 63, 64, 65, 67, 71, 72, 73, 74, 75, 76, 78, 81, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 96, 97, 98, 99.
%t A160234 s="1";ss={};Do[tsn=ToString[n];If[ !StringFreeQ[s,tsn],AppendTo[ss,n]];s=s<>tsn,{n,2,99999}];Table[Length[Select[ss,10^(n-1)<=#<10^n&]],{n,1,5}]
%o A160234 (Python)
%o A160234 from itertools import count, islice
%o A160234 def agen(): # generator of terms
%o A160234     s = ""
%o A160234     for digits in count(1):
%o A160234         c = 0
%o A160234         for k in range(10**(digits-1), 10**digits):
%o A160234             sk = str(k)
%o A160234             if sk in s: c += 1
%o A160234             s += sk
%o A160234         yield c
%o A160234 print(list(islice(agen(), 5))) # _Michael S. Branicky_, Mar 17 2022
%Y A160234 Cf. A116700 ("Early bird" numbers).
%K A160234 base,nonn,more
%O A160234 1,2
%A A160234 _Zak Seidov_, May 04 2009
%E A160234 a(6)-a(7) from _Michael S. Branicky_, Mar 17 2022
%E A160234 a(8) from _Michael S. Branicky_, Dec 21 2022
%E A160234 a(9)-a(10) from _Michael S. Branicky_, Feb 06 2023