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 A094151 #20 May 21 2024 17:00:00
%S A094151 0,1,0,3,4,3,4,7,0,9,4,3,12,9,9,7,1,9,7,19,12,15,18,15,24,9,0,11,27,9,
%T A094151 7,7,15,9,9,27,29,21,21,39,22,33,5,15,9,39,45,39,39,49,27,51,33,27,4,
%U A094151 23,15,49,49,39,32,13,54,7,9,15,41,59,0,39,47,63,41,17,24,23,37,21,75,39
%N A094151 Remainder when concatenation 1,2,3,...up to (n-1) is divided by n.
%H A094151 Michael S. Branicky, <a href="/A094151/b094151.txt">Table of n, a(n) for n = 1..10000</a>
%F A094151 a(n) = A007908(n-1) mod n for n>1. - _Michel Marcus_, Nov 21 2022
%e A094151 a(5) = 15 hence a(6) = least integer multiple of 15/6 = 5.
%t A094151 Table[st = ""; For[i = 0, i <= n - 1, i++, st = st <> ToString[i]]; Mod[ ToExpression[st], n], {n, 1, 100}] (* Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 12 2004 *)
%t A094151 Table[Mod[FromDigits[Flatten[IntegerDigits/@Range[n-1]]],n],{n,100}] (* _Harvey P. Dale_, May 21 2024 *)
%o A094151 (Python)
%o A094151 from itertools import count, islice
%o A094151 def agen():
%o A094151 s = "0"
%o A094151 for n in count(1): yield int(s)%n; s += str(n)
%o A094151 print(list(islice(agen(), 80))) # _Michael S. Branicky_, Nov 21 2022
%o A094151 (PARI) a(n)=if(n<=9, return(1719%n)); my(m=Mod(123456789,n)); for(d=2,#Str(n-1), my(D=10^d); for(k=D/10,min(D,n)-1, m=D*m+k)); lift(m) \\ _Charles R Greathouse IV_, Nov 21 2022
%Y A094151 Cf. A007908, A110740 (indices of 0's).
%Y A094151 Cf. A095221.
%K A094151 nonn,base,easy
%O A094151 1,4
%A A094151 _Amarnath Murthy_, Apr 29 2004
%E A094151 More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 12 2004