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 A038489 #14 Apr 05 2025 15:31:34
%S A038489 820,6652,7300,7372,7380,59140,59788,59860,59868,65620,65692,65700,
%T A038489 66340,66348,66420,531532,532180,532252,532260,538012,538084,538092,
%U A038489 538732,538740,538812,590500,590572,590580,591220,591228,591300,597052,597060,597132,597780,4783060
%N A038489 Sums of 4 distinct powers of 9.
%H A038489 Amiram Eldar, <a href="/A038489/b038489.txt">Table of n, a(n) for n = 1..10000</a>
%t A038489 Sort[Plus @@@ Subsets[9^Range[0, 6], {4}]] (* _Amiram Eldar_, Jul 14 2022 *)
%o A038489 (Python)
%o A038489 from itertools import islice
%o A038489 def A038489_gen(): # generator of terms
%o A038489 yield int(bin(n:=15)[2:],9)
%o A038489 while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:],9)
%o A038489 A038489_list = list(islice(A038489_gen(),30)) # _Chai Wah Wu_, Apr 05 2025
%Y A038489 Base-9 interpretation of A038446.
%Y A038489 Cf. A001019, A038487, A038488.
%K A038489 nonn,easy
%O A038489 1,1
%A A038489 _Olivier Gérard_
%E A038489 Offset corrected by _Amiram Eldar_, Jul 14 2022