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 A377228 #21 Jan 07 2025 19:07:10
%S A377228 1,2,3,4,5,6,7,8,9,111,222,333,444,555,666,777,888,999,111111111,
%T A377228 222222222,333333333,444444444,555555555,666666666,777777777,
%U A377228 888888888,999999999,111111111111111111111111111,222222222222222222222222222,333333333333333333333333333,444444444444444444444444444
%N A377228 Repdigits which are also Harshad numbers.
%e A377228 999 is in the sequence as it is a repdigit (all digits are equal (in base 10)) and 999 is divisible by its sum of digits; 9 + 9 + 9 = 27 is a divisors of 999. - _David A. Corneth_, Oct 20 2024
%t A377228 Select[Union[FromDigits/@Flatten[Table[PadRight[{}, i, n], {n, 9}, {i, 27}], 1]],Divisible[#,DigitSum[#]]&] (* _James C. McMahon_, Jan 07 2025 *)
%o A377228 (PARI) repd(n) = 10^((n+8)\9)\9*((n-1)%9+1); \\ A010785
%o A377228 lista(nn) = select(x->(x%sumdigits(x)==0), vector(nn, k, repd(k))); \\ _Michel Marcus_, Jan 07 2025
%Y A377228 Intersection of A005349 and A010785.
%Y A377228 Cf. A014950.
%K A377228 nonn,base
%O A377228 1,2
%A A377228 _John Bibby_, Oct 20 2024
%E A377228 More terms from _David A. Corneth_, Oct 20 2024