A253049 Numbers in A098550 which appear immediately after a prime.

3, 4, 6, 10, 13, 33, 18, 42, 48, 31, 58, 70, 43, 82, 90, 102, 110, 120, 126, 140, 144, 154, 150, 182, 180, 198, 200, 220, 216, 228, 272, 252, 280, 270, 300, 306, 312, 330, 336, 340, 348, 360, 390, 392, 396, 400, 442, 438, 468, 440, 506, 480, 484, 500, 486, 518, 528, 540, 574, 546, 570, 572, 616

Offset: 1

Author

N. J. A. Sloane, Dec 27 2014

Keywords

• nonn

Comments

It is conjectured that this is the same as A253048 except for the addition of 3, 13, 31, and 43 (the upper members of the twin primes in A098550).

a(n) = A098550(A251239(n)+1). - Reinhard Zumkeller, Dec 29 2014

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, 2015 and J. Int. Seq. 18 (2015) 15.6.7.

Crossrefs

Cf. A098550. See A253048 for another version.

Cf. A251239.

Programs

Mathematica

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}, 1000];
sp = SequencePosition[A098550, {?PrimeQ, }] [[All, 2]];
A098550[[sp]] (* Jean-François Alcover, Sep 03 2018, after Robert G. Wilson v in A098550 *)