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 A004690 #19 Sep 08 2022 08:44:33
%S A004690 0,1,1,2,3,5,11,16,30,46,106,155,264,452,1046,1531,2610,4441,10351,
%T A004690 15122,25503,43625,102431,146356,252120,431506,1013626,1445435,
%U A004690 2462364,4241132,10033526,14304661,24341520
%N A004690 Fibonacci numbers written in base 7.
%H A004690 Vincenzo Librandi, <a href="/A004690/b004690.txt">Table of n, a(n) for n = 0..1000</a>
%t A004690 Table[BaseForm[Fibonacci[n],7],{n,1,20,1}] (* _Vladimir Joseph Stephan Orlovsky_, Jul 23 2008 *)
%t A004690 FromDigits[IntegerDigits[#, 7]] & / @ Fibonacci[Range[0, 40]] (* _Vincenzo Librandi_, Jun 08 2013 *)
%o A004690 (PARI) a(n)=fromdigits(digits(fibonacci(n),7)) \\ _Charles R Greathouse IV_, Oct 28 2014
%o A004690 (Magma) [Seqint(Intseq(Fibonacci(n),7)): n in [0..50]]; // _G. C. Greubel_, Oct 09 2018
%Y A004690 Cf. A000045 (Fibonacci), A007093 (numbers in base 7).
%K A004690 nonn,base,easy
%O A004690 0,4
%A A004690 _N. J. A. Sloane_