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A306877 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. 1

%I

%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

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Last modified February 17 15:32 EST 2020. Contains 331998 sequences. (Running on oeis4.)