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A163990
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Square array read by antidiagonals where the row n lists the numbers k such that their largest divisor <= sqrt(k) equals n.
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6
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1, 4, 2, 9, 6, 3, 16, 12, 8, 5, 25, 20, 15, 10, 7, 36, 30, 24, 18, 14, 11, 49, 42, 35, 28, 21, 22, 13, 64, 56, 48, 40, 32, 27, 26, 17, 81, 72, 63, 54, 45, 44, 33, 34, 19, 100, 90, 80, 70, 60, 50, 52, 39, 38, 23, 121, 110, 99, 88, 77, 66, 55, 68, 51, 46, 29, 144, 132, 120, 108
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OFFSET
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1,2
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COMMENTS
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This sequence is a permutation of the natural numbers.
Note that the first row is formed by 1 together the prime numbers and the first column are the squares of the natural numbers.
For more information see A163280, the main entry for this sequence. (See also A161344).
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LINKS
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Table of n, a(n) for n=1..70.
Index entries for sequences that are permutations of the natural numbers
O. E. Pol, Illustration for A008578, the first row of the array [From Omar E. Pol, Oct 24 2009]
O. E. Pol, Illustration for A161344, the second row of the array [From Omar E. Pol, Oct 24 2009]
O. E. Pol, Illustration for A008578, A161344, A161345 and A161424 [From Omar E. Pol, Oct 24 2009]
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FORMULA
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Row n lists the numbers k such that A033676(k)=n.
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EXAMPLE
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Array begins:
1, 2, 3, 5, 7, 11,
4, 6, 8, 10, 14,
9, 12, 15, 18,
16, 20, 24,
25, 30,
36,
See also the array in A163280.
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CROSSREFS
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Cf. A000027, A000040, A033676, A147861, A163100, A163280, A163281, A163991, A164000.
Cf. Rows: 1=A008578, 2=A161344, 3=A161345, 4=A161424, 5=A161835, 6=A162526, 7=A162527, 8=A162528, 9=A162529, 10=A162530, 11=A162531, 12=A162532.
Cf. Columns: 1=A000290, 2=A002378, 4=A164004, 6=A164006, 7=A164007, 8=A164008, 9=A164009, 10=A164010, 11=A164011, 12=A164012.
Sequence in context: A008831 A213778 A095833 * A082156 A114577 A191426
Adjacent sequences: A163987 A163988 A163989 * A163991 A163992 A163993
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KEYWORD
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nonn,tabl
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AUTHOR
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Omar E. Pol, Aug 11 2009
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STATUS
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approved
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