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A251539 First differences of A251538. 6
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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

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Last modified February 18 03:40 EST 2020. Contains 332006 sequences. (Running on oeis4.)