A251539 - OEIS

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

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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&];