login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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: A052168 A237152 A306864 * A073495 A073489 A232040

Adjacent sequences:  A306874 A306875 A306876 * A306878 A306879 A306880

KEYWORD

nonn,look

AUTHOR

Rémy Sigrist, Mar 14 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 20:41 EST 2020. Contains 331066 sequences. (Running on oeis4.)