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A285386
Lexicographically earliest sequence of distinct positive terms such that the product of two consecutive terms is divisible by p^4 for some prime p.
2
1, 16, 2, 8, 4, 12, 20, 24, 6, 27, 3, 32, 5, 48, 7, 64, 9, 18, 36, 28, 40, 10, 56, 14, 72, 22, 80, 11, 81, 13, 96, 15, 54, 21, 108, 30, 88, 26, 104, 34, 112, 17, 128, 19, 144, 23, 160, 25, 50, 75, 100, 44, 52, 60, 68, 76, 84, 92, 116, 120, 38, 136, 42, 135, 33
OFFSET
1,2
COMMENTS
This sequence is a permutation of the natural numbers.
EXAMPLE
The first terms, alongside the primes p such that p^4 divides a(n)*a(n+1), are:
n a(n) p
-- ---- -
1 1 2
2 16 2
3 2 2
4 8 2
5 4 2
6 12 2
7 20 2
8 24 2
9 6 3
10 27 3
11 3 2
12 32 2
13 5 2
14 48 2
15 7 2
16 64 2
17 9 3
18 18 3
19 36 2
20 28 2
...
165 95 2
166 432 2, 3
167 87 3
...
CROSSREFS
Cf. A285296.
Sequence in context: A040253 A180730 A040254 * A100079 A144532 A270570
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Apr 18 2017
STATUS
approved