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 A241787 #21 Oct 25 2023 02:19:19 %S A241787 1035,1275,1326,1378,1485,1540,1596,1653,1830,1953,2016,2145,2346, %T A241787 2415,2485,2701,2850,3081,3160,3240,3486,3570,3741,3916,4095,4186, %U A241787 4278,4371,4560,4753,4851,4950,5460,5671,6105,6328,6903,7021,7140,7260,7381,7503,8256 %N A241787 Triangular numbers which have one or more occurrences of exactly four different digits. %C A241787 The first term having a repeated digit is 10153. %H A241787 Colin Barker, <a href="/A241787/b241787.txt">Table of n, a(n) for n = 1..2000</a> %t A241787 Select[Accumulate[Range[200]],Count[DigitCount[#],0]==6&] (* _Harvey P. Dale_, Jun 29 2022 *) %o A241787 (PARI) s=[]; for(n=0, 300, if(#vecsort(eval(Vec(Str(n*(n+1)/2))), , 8)==4, s=concat(s, n*(n+1)/2))); s %Y A241787 Cf. A045914, A062691, A162304, A241788, A241789, A241790, A241791, A241792, A241812. %Y A241787 Cf. A000217. %K A241787 nonn,base %O A241787 1,1 %A A241787 _Colin Barker_, Apr 28 2014