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 A141579 #14 Jul 04 2025 06:08:49
%S A141579 1,2,47,53,94,103,106,163,199,206,257,269,311,326,397,398,401,419,421,
%T A141579 499,514,538,587,599,617,622,683,757,773,794,802,838,842,863,883,907,
%U A141579 911,929,991,998,1021,1087,1109,1123,1174,1181,1198,1210,1234,1237,1291
%N A141579 Numbers k such that the arithmetic mean of the first k tribonacci numbers A000073 is an integer.
%C A141579 Numbers in this sequence but not in A140973 are 2021 and 2090 (but no others below 8400). - _Emeric Deutsch_, Aug 19 2008.
%H A141579 Amiram Eldar, <a href="/A141579/b141579.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1500 from Harvey P. Dale)
%F A141579 {k: k | A008937(k-2)}.
%p A141579 A000073 := proc(n) option remember ; if n <= 1 then 0 ; elif n =2 then 1 ; else procname(n-1)+procname(n-2)+procname(n-3) ; fi; end: A008937 := proc(n) option remember ; add(A000073(i),i=0..n+1) ; end: isA := proc(n) if n = 1 then RETURN(true) ; fi; if A008937(n-2) mod n = 0 then true; else false ; fi; end: for n from 1 to 2000 do if isA(n) then printf("%d,",n) ; fi; od ;
%t A141579 Module[{nn=1300,tnos},tnos=LinearRecurrence[{1,1,1},{0,0,1},nn];Position[ Table[Mean[Take[tnos,n]],{n,nn}],_?(IntegerQ[#]&)]]//Flatten (* _Harvey P. Dale_, Oct 05 2020 *)
%Y A141579 Cf. A000073, A008937, A140973.
%K A141579 nonn
%O A141579 1,2
%A A141579 _R. J. Mathar_, Aug 19 2008