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 A217535 #7 Jun 25 2017 08:34:07 %S A217535 1023456789,10012233445566778899,100011222333444555666777888999, %T A217535 1000011122223333444455556666777788889999, %U A217535 10000011112222233333444445555566666777778888899999,100000011111222222333333444444555555666666777777888888999999 %N A217535 Least number having in its decimal representation each digit n times. %H A217535 Alois P. Heinz, <a href="/A217535/b217535.txt">Table of n, a(n) for n = 1..100</a> %F A217535 a(n) ~ 10^(10n-1). See PARI code for an exact formula. %p A217535 a:= n-> parse(cat(1,0$n,1$(n-1),seq(i$n, i=2..9))): %p A217535 seq(a(n), n=1..10); # _Alois P. Heinz_, Jun 25 2017 %o A217535 (PARI) A217535(n)=sum(d=1,9,10^(n-(d==1))\9*d*10^(n*(9-d)))+10^(10*n-1) %Y A217535 Cf. A050278, A051018, A049363, A074205, A154566, A204047, A020666, A020667, A061604, A180489. %Y A217535 A subsequence of A171102. %K A217535 nonn,base,easy %O A217535 1,1 %A A217535 _M. F. Hasler_, Oct 05 2012