This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A251557 a(n) = 2 more than the largest even number among {A098550(1), A098550(2), ..., A098550(n)}. 5
 2, 4, 4, 6, 6, 10, 10, 16, 16, 16, 16, 16, 16, 18, 18, 18, 18, 22, 22, 24, 24, 24, 24, 24, 28, 28, 30, 30, 34, 34, 34, 34, 34, 34, 36, 36, 38, 38, 38, 38, 40, 40, 40, 44, 44, 46, 46, 46, 46, 52, 52, 52, 52, 54, 54, 54, 54, 58, 58, 64, 64, 64, 64, 64, 66, 66, 70, 70, 70, 70, 70, 70, 70 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 David L. Applegate, Hans Havermann, Bob Selcoe, Vladimir Shevelev, N. J. A. Sloane, and Reinhard Zumkeller, The Yellowstone Permutation, arXiv preprint arXiv:1501.01669 [math.NT], 2015 and J. Int. Seq. 18 (2015) 15.6.7. MATHEMATICA terms = 100; f[lst_] := Block[{k = 4}, While[GCD[lst[[-2]], k] == 1 || GCD[lst[[-1]], k] > 1 || MemberQ[lst, k], k++]; Append[lst, k]]; A098550 = Nest[f, {1, 2, 3}, terms - 3]; a[1] = 2; a[n_] := Max[Select[A098550[[1 ;; n]], EvenQ]] + 2; Array[a, terms] (* Jean-François Alcover, Aug 02 2018, after Robert G. Wilson v *) PROG (Haskell) a251557 n = a251557_list !! (n-1) a251557_list = map (+ 2) \$ tail \$ scanl maxEven 0 a098550_list                where maxEven u v = if even v then max u v else u -- Reinhard Zumkeller, Mar 10 2015 CROSSREFS Cf. A098550, A251546, A251558, A251559. Sequence in context: A087554 A281072 A226951 * A231901 A135974 A153494 Adjacent sequences:  A251554 A251555 A251556 * A251558 A251559 A251560 KEYWORD nonn AUTHOR N. J. A. Sloane, Dec 23 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 19 19:41 EDT 2018. Contains 313896 sequences. (Running on oeis4.)