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A338219
Lexicographically earliest divisibility sequence consisting only of distinct squarefree numbers.
2
1, 2, 3, 6, 5, 30, 7, 42, 15, 10, 11, 210, 13, 14, 105, 462, 17, 330, 19, 390, 21, 22, 23, 2310, 35, 26, 165, 546, 29, 2730, 31, 6006, 33, 34, 70, 30030, 37, 38, 39, 46410, 41, 3570, 43, 66, 1155, 46, 47, 39270, 77, 770, 51, 78, 53, 4290, 55, 9282, 57, 58, 59
OFFSET
1,2
COMMENTS
This sequence is a permutation of the squarefree numbers (A005117).
FORMULA
a(p) = p for any prime number p.
a(p) < a(n) for any prime number p and n > p.
EXAMPLE
For n = 1:
- we choose a(1) = 1.
For n = 2:
- a(2) must be divisible by a(1) = 1,
- we choose a(2) = 2.
For n = 3:
- a(3) must be divisible by a(1) = 1,
- we choose a(3) = 3.
For n = 4:
- a(4) must be divisible by a(1) = 1 and a(2) = 2,
- we choose a(4) = 6.
For n = 5:
- a(5) must be divisible by a(1) = 1,
- we choose a(5) = 5.
For n = 6:
- a(6) must be divisible by a(1) = 1, a(2) = 2 and a(3) = 3,
- we choose a(6) = 30.
PROG
(PARI) See Links section.
CROSSREFS
See A338461 for a similar sequence.
Sequence in context: A206242 A327454 A124655 * A066838 A228151 A276087
KEYWORD
nonn,look
AUTHOR
Rémy Sigrist, Jan 30 2021
STATUS
approved