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A306864
Lexicographically earliest sequence of distinct positive terms such that among the prime divisors of the product of two consecutive terms there are at least 4 runs of consecutive prime numbers.
2
1, 1870, 2, 935, 4, 1045, 8, 1235, 10, 187, 20, 209, 40, 247, 14, 299, 21, 377, 28, 391, 22, 85, 44, 95, 26, 115, 34, 55, 38, 65, 46, 91, 57, 182, 19, 110, 17, 220, 23, 130, 29, 170, 11, 190, 13, 230, 31, 238, 37, 260, 41, 266, 39, 133, 52, 145, 68, 155, 76
OFFSET
1,2
COMMENTS
This sequence is a variant of A285487.
This sequence is likely a permutation of the natural numbers.
FORMULA
A287170(a(n) * a(n+1)) >= 4.
EXAMPLE
The first terms, alongside the corresponding runs, are:
n a(n) runs in a(n)*a(n+1)
--- ---- -------------------
1 1 2, 5, 11, 17
2 1870 2, 5, 11, 17
3 2 2, 5, 11, 17
4 935 2, 5, 11, 17
5 4 2, 5, 11, 19
6 1045 2, 5, 11, 19
7 8 2, 5, 13, 19
8 1235 2, 5, 13, 19
9 10 2, 5, 11, 17
10 187 2, 5, 11, 17
11 20 2, 5, 11, 19
12 209 2, 5, 11, 19
...
32 91 3, 7, 13, 19
33 57 2-3, 7, 13, 19
34 182 2, 7, 13, 19
...
662 1222 2, 7, 13, 47
663 448 2, 7, 17, 73
664 1241 2-3, 7-11, 17, 73
665 462 2-3, 7-11, 29, 43
666 1247 3, 17, 29, 43
...
PROG
(PARI) See Links section.
CROSSREFS
Sequence in context: A052168 A354444 A237152 * A306877 A073495 A073489
KEYWORD
nonn,look
AUTHOR
Rémy Sigrist, Mar 14 2019
STATUS
approved