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A056538
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Replace n by its divisors in reverse order.
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9
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1, 2, 1, 3, 1, 4, 2, 1, 5, 1, 6, 3, 2, 1, 7, 1, 8, 4, 2, 1, 9, 3, 1, 10, 5, 2, 1, 11, 1, 12, 6, 4, 3, 2, 1, 13, 1, 14, 7, 2, 1, 15, 5, 3, 1, 16, 8, 4, 2, 1, 17, 1, 18, 9, 6, 3, 2, 1, 19, 1, 20, 10, 5, 4, 2, 1, 21, 7, 3, 1, 22, 11, 2, 1, 23, 1, 24, 12, 8, 6, 4, 3, 2, 1, 25, 5, 1, 26, 13, 2, 1, 27, 9
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| This gives the second elements of the ordered pairs (a,b) a >= 1, b >= 1 ordered by their product ab.
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LINKS
| O. E. Pol, Illustration of the divisors of n [From Omar E. Pol (info(AT)polprimos.com), Nov 22 2009]
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EXAMPLE
| Contribution from Omar E. Pol (info(AT)polprimos.com), Nov 22 2009: (Start)
Triangle begins:
1;
2, 1;
3, 1;
4, 2, 1;
5, 1;
6, 3, 2, 1;
7, 1;
8, 4, 2, 1;
9, 3, 1;
10, 5, 2, 1;
11, 1;
12, 6, 4, 3, 2, 1;
13, 1;
14, 7, 2, 1;
15, 5, 3, 1;
16, 8, 4, 2, 1;
17, 1;
18, 9, 6, 3, 2, 1;
19, 1;
20, 10, 5, 4, 2, 1;
(End)
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MAPLE
| map(op, [seq(reverse(sort(divisors(j))), j=1..30)]);
cdr := proc(l) if 0 = nops(l) then ([]) else (l[2..nops(l)]): fi: end:
reverse := proc(l) if 0 = nops(l) then ([]) else [op(reverse(cdr(l))), l[1]]; fi: end:
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PROG
| (MAGMA) [Reverse(Divisors(n)) : n in [1..30]];
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CROSSREFS
| Cf. A027750 for the first elements, A056534.
a(n) = A064894(A064896(n))
Cf. A168017. [From Omar E. Pol (info(AT)polprimos.com), Nov 22 2009]
Sequence in context: A087114 A088242 A113398 * A120385 A195836 A132460
Adjacent sequences: A056535 A056536 A056537 * A056539 A056540 A056541
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KEYWORD
| nonn,tabf
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AUTHOR
| Antti Karttunen Jun 20, 2000
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