A306877 - OEIS

%I #16 Mar 21 2019 04:37:50

%S 1870,935,1729,1045,374,2093,494,1235,2639,187,170,2737,190,247,4301,

%T 1265,110,2821,130,209,299,85,182,3367,418,95,3451,377,220,5423,230,

%U 1495,391,55,598,3458,238,65,133,253,260,403,266,115,5797,91,273,3689,741,319

%N Lexicographically earliest sequence of distinct positive terms such that, for any n > 0, among the prime divisors of n * a(n) there are at least 4 runs of consecutive prime numbers.

%C This sequence is a variant of A285744 and of A306864.

%C This sequence is a self-inverse permutation of the natural numbers.

%H Rémy Sigrist, <a href="/A306877/b306877.txt">Table of n, a(n) for n = 1..30000</a>

%H Rémy Sigrist, <a href="/A306877/a306877.gp.txt">PARI program for A306877</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%F A287170(n * a(n)) >= 4.

%e The first terms, alongside the corresponding runs, are:

%e   n   a(n)  runs in n*a(n)

%e   --  ----  --------------

%e    1  1870  2, 5, 11, 17

%e    2   935  2, 5, 11, 17

%e    3  1729  3, 7, 13, 19

%e    4  1045  2, 5, 11, 19

%e    5   374  2, 5, 11, 17

%e    6  2093  2-3, 7, 13, 23

%e    7   494  2, 7, 13, 19

%e    8  1235  2, 5, 13, 19

%e    9  2639  3, 7, 13, 29

%e   10   187  2, 5, 11, 17

%e   11   170  2, 5, 11, 17

%e   12  2737  2-3, 7, 17, 23

%e   13   190  2, 5, 13, 19

%e   14   247  2, 7, 13, 19

%e   15  4301  3-5, 11, 17, 23

%e   16  1265  2, 5, 11, 23

%o (PARI) See Links section.

%Y Cf. A285744, A287170, A306864.

%K nonn,look

%O 1,1

%A _Rémy Sigrist_, Mar 14 2019