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A334390
Lexicographically earliest sequence of distinct positive integers such that for any n > 0, a(n), a(2*n) and a(2*n+1) are in geometric progression.
2
1, 2, 4, 6, 18, 8, 16, 12, 24, 30, 50, 28, 98, 20, 25, 36, 108, 48, 96, 60, 120, 40, 32, 14, 7, 84, 72, 10, 5, 15, 9, 42, 49, 54, 27, 132, 363, 144, 216, 90, 135, 180, 270, 80, 160, 64, 128, 56, 224, 21, 63, 126, 189, 156, 338, 70, 490, 35, 245, 75, 375, 33
OFFSET
1,2
COMMENTS
This sequence is a variant of A305410; here we consider geometric progressions, there arithmetic progressions.
LINKS
EXAMPLE
The first terms, alongside the corresponding common ratios, are:
n a(n) a(2*n) a(2*n+1) r
-- ---- ------ -------- ---
1 1 2 4 2
2 2 6 18 3
3 4 8 16 2
4 6 12 24 2
5 18 30 50 5/3
6 8 28 98 7/2
7 16 20 25 5/4
8 12 36 108 3
9 24 48 96 2
10 30 60 120 2
PROG
(PARI) See Links section.
CROSSREFS
Sequence in context: A294920 A046441 A192335 * A067993 A074131 A355078
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Apr 26 2020
STATUS
approved