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A137621 Divisors of nonprimes not occurring earlier. 6
1, 2, 4, 3, 6, 8, 9, 5, 10, 12, 7, 14, 15, 16, 18, 20, 21, 11, 22, 24, 25, 13, 26, 27, 28, 30, 32, 33, 17, 34, 35, 36, 19, 38, 39, 40, 42, 44, 45, 23, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 29, 58, 60, 31, 62, 63, 64, 65, 66, 68, 69, 70, 72, 37, 74, 75, 76, 77, 78, 80, 81, 41 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Permutation with inverse A137622; A137623(n) = a(a(n)).

a(A120632(n))=A000040(n); a(A120632(n)+1)=A100484(n); a(A137624(n))=A018252(n).

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10001

Index entries for sequences that are permutations of the natural numbers

EXAMPLE

1;2,4;3,6;8;9;5,10;12;7,14;15;16;18;20;21;11,22;24; .. .

CROSSREFS

Sequence in context: A280864 A266411 A264740 * A242705 A039864 A101906

Adjacent sequences:  A137618 A137619 A137620 * A137622 A137623 A137624

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jan 30 2008

STATUS

approved

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Last modified October 22 18:51 EDT 2020. Contains 337953 sequences. (Running on oeis4.)