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URL: https://oeis.org/A306877

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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

1870, 935, 1729, 1045, 374, 2093, 494, 1235, 2639, 187, 170, 2737, 190, 247, 4301, 1265, 110, 2821, 130, 209, 299, 85, 182, 3367, 418, 95, 3451, 377, 220, 5423, 230, 1495, 391, 55, 598, 3458, 238, 65, 133, 253, 260, 403, 266, 115, 5797, 91, 273, 3689, 741, 319

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

This sequence is a variant of A285744 and of A306864.

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

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..30000

Rémy Sigrist, PARI program for A306877

Index entries for sequences that are permutations of the natural numbers

FORMULA

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

EXAMPLE

The first terms, alongside the corresponding runs, are:

n a(n) runs in n*a(n)

-- ---- --------------

1 1870 2, 5, 11, 17

2 935 2, 5, 11, 17

3 1729 3, 7, 13, 19

4 1045 2, 5, 11, 19

5 374 2, 5, 11, 17

6 2093 2-3, 7, 13, 23

7 494 2, 7, 13, 19

8 1235 2, 5, 13, 19

9 2639 3, 7, 13, 29

10 187 2, 5, 11, 17

11 170 2, 5, 11, 17

12 2737 2-3, 7, 17, 23

13 190 2, 5, 13, 19

14 247 2, 7, 13, 19

15 4301 3-5, 11, 17, 23

16 1265 2, 5, 11, 23

PROG

(PARI) See Links section.

CROSSREFS

Cf. A285744, A287170, A306864.

Sequence in context: A354444 A237152 A306864 * A073495 A073489 A353552

Adjacent sequences: A306874 A306875 A306876 * A306878 A306879 A306880

KEYWORD

nonn,look

AUTHOR

Rémy Sigrist, Mar 14 2019

STATUS

approved