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 A038491 #15 Apr 05 2025 18:26:21
%S A038491 133,1343,1453,1463,14653,14763,14773,15973,15983,16093,161063,161173,
%T A038491 161183,162383,162393,162503,175693,175703,175813,177023,1771573,
%U A038491 1771683,1771693,1772893,1772903,1773013,1786203,1786213,1786323
%N A038491 Sums of 3 distinct powers of 11.
%H A038491 Robert Israel, <a href="/A038491/b038491.txt">Table of n, a(n) for n = 0..10000</a>
%F A038491 a(A000292(m+1)+k) = a(A000292(m)+k) + 10*11^(m+2) for 0<=k<=A000217(m). - _Robert Israel_, Dec 23 2016
%p A038491 seq(seq(seq(11^a+11^b+11^c,c=0..b-1),b=1..a-1),a=2..10); # _Robert Israel_, Dec 23 2016
%t A038491 TakeWhile[#, # <= 1800000 &] &@ Sort@ Map[Total, 11^Subsets[Range[0, 8], {3}]] (* _Michael De Vlieger_, Dec 23 2016 *)
%o A038491 (Python)
%o A038491 from math import isqrt, comb
%o A038491 from sympy import integer_nthroot
%o A038491 def A038491(n): return 11**((r:=n-1-comb((m:=integer_nthroot(6*n,3)[0])+(t:=(n>comb(m+2,3)))+1,3))-comb((k:=isqrt(b:=r+1<<1))+(b>k*(k+1)),2))+11**((a:=isqrt(s:=n-comb(m-(t^1)+2,3)<<1))+((s<<2)>(a<<2)*(a+1)+1))+11**(m+t+1) # _Chai Wah Wu_, Apr 05 2025
%Y A038491 Base-11 interpretation of A038445.
%Y A038491 Cf. A000217, A000292.
%K A038491 nonn,easy
%O A038491 0,1
%A A038491 _Olivier Gérard_