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 A232666 #12 Feb 28 2018 15:22:28 %S A232666 0,1,1,2,3,5,8,13,21,34,55,89,4,93,97,190,287,477,764,1241,2005,541, %T A232666 2546,3087,5633,8720,14353,23073,37426,60499,97925,26404,124329, %U A232666 150733,275062,425795,700857,1126652,1827509,2954161,796945,3751106,4548051,8299157,12847208,21146365,33993573 %N A232666 6-free Fibonacci numbers. %C A232666 The sequences of n-free Fibonacci numbers were suggested by John H. Conway. %C A232666 a(n) is the sum of the two previous terms divided by the largest possible power of 6. %C A232666 4-free Fibonacci numbers are A224382. %C A232666 The sequence coincides with the Fibonacci sequence until the first multiple of 6 in the Fibonacci sequence: 144, which in this sequence is divided by 36 to produce 4. %C A232666 7-free Fibonacci numbers is A078414. %H A232666 B. Avila, T. Khovanova, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL17/Avila/avila4.html">Free Fibonacci Sequences</a>, J. Int. Seq. 17 (2014) # 14.8.5. %t A232666 sixPower[n_] := (a = Transpose[FactorInteger[n]]; a2 = Position[a[[1]], 2]; a3 = Position[a[[1]], 3]; If[Length[a2] == 0 || Length[a3] == 0 , res = 0, res = Min[a[[2]][[a2[[1]][[1]]]], a[[2]][[a3[[1]][[1]]]]]]; res); sixFree[n_] := n/6^sixPower[n]; appendNext6Free[list_] := Append[list, sixFree[list[[-1]] + list[[-2]]]]; Nest[appendNext6Free, {0, 1}, 50] %Y A232666 Cf. A224382, A214684. %K A232666 nonn %O A232666 0,4 %A A232666 _Brandon Avila_ and _Tanya Khovanova_, Nov 27 2013