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.
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
Offset: 1
Examples
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
Links
Programs
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PARI
See Links section.
Formula
A287170(n * a(n)) >= 4.
Comments