A251539 First differences of A251538.

4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 1, 1, 1, 2, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4

Offset

1,1

Comments

I would very much like to have a formula or recurrence for this sequence.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..100000

Mathematica

max = 1000 (* = max term of A251538 *);
A098548 = {1, 2, 3};
For[n = 4, n <= 8 max, n++, If[GCD[n, A098548[[-1]]] == 1 && GCD[n, A098548[[-2]]] > 1, AppendTo[A098548, n]]];
A251538 = Select[Range[max], A098548[[2#+3]] > A098548[[2#+1]] + 6&];
Differences[A251538] (* Jean-François Alcover, Aug 01 2018 *)

Prog

(Haskell)
a251539 n = a251539_list !! (n-1)
a251539_list = zipWith (-) (tail a251538_list) a251538_list
-- Reinhard Zumkeller, Dec 08 2014

Crossrefs

Cf. A098548, A251535-A251538.

Cf. A251767 (duplicates removed), A251768 (run lengths).

Sequence in context: A136213 A088848 A088849 * A123932 A010709 A138908

Adjacent sequences: A251536 A251537 A251538 * A251540 A251541 A251542

Keyword

nonn

Author

N. J. A. Sloane, Dec 07 2014

Status

approved