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A331010
Lexicographically earliest sequence of distinct positive terms that can be viewed as an irregular table where the n-th row has A000005(a(n)) terms and T(n, k) is a multiple of the k-th divisor of a(n) (=A027750(a(n), k)).
4
1, 2, 4, 3, 6, 8, 5, 9, 7, 10, 12, 18, 11, 14, 16, 24, 13, 15, 17, 21, 27, 19, 28, 20, 22, 25, 30, 23, 26, 33, 32, 36, 48, 29, 34, 39, 42, 45, 54, 31, 44, 35, 38, 49, 56, 37, 40, 52, 64, 80, 41, 46, 51, 60, 66, 72, 84, 96, 43, 65, 47, 57, 50, 75, 53, 68, 55
OFFSET
1,2
COMMENTS
This sequence is a permutation of the natural numbers as each row starts with the least value not yet in the sequence.
The prime numbers appear in ascending order.
EXAMPLE
The first terms and rows are:
n a(n) row(n)
-- ---- -------------------------
1 1 [1]
2 2 [2, 4]
3 4 [3, 6, 8]
4 3 [5, 9]
5 6 [7, 10, 12, 18]
6 8 [11, 14, 16, 24]
7 5 [13, 15]
8 9 [17, 21, 27]
9 7 [19, 28]
10 10 [20, 22, 25, 30]
11 12 [23, 26, 33, 32, 36, 48]
12 18 [29, 34, 39, 42, 45, 54]
13 11 [31, 44]
14 14 [35, 38, 49, 56]
15 16 [37, 40, 52, 64, 80]
16 24 [41, 46, 51, 60, 66, 72, 84, 96]
PROG
(PARI) See Links section.
CROSSREFS
See A331016, A331018 and A331026 for similar sequences.
Sequence in context: A178898 A296616 A143529 * A261351 A249054 A103867
KEYWORD
nonn,look,tabf
AUTHOR
Rémy Sigrist, Jan 06 2020
STATUS
approved