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A210976
Square array T(n,k), n>=1, k>=1, read by antidiagonals in which column k lists the positive integers whose number of divisors is not k.
3
2, 3, 1, 4, 4, 1, 5, 6, 2, 1, 6, 8, 3, 2, 1, 7, 9, 5, 3, 2, 1, 8, 10, 6, 4, 3, 2, 1, 9, 12, 7, 5, 4, 3, 2, 1, 10, 14, 8, 7, 5, 4, 3, 2, 1, 11, 15, 10, 9, 6, 5, 4, 3, 2, 1, 12, 16, 11, 11, 7, 6, 5, 4, 3, 2, 1, 13, 18, 12, 12, 8, 7, 6, 5, 4, 3, 2, 1, 14, 20
OFFSET
1,1
COMMENTS
Column k lists the numbers j such that A000005(j) <> k.
EXAMPLE
Column 2 lists the nonprimes A018252 because they are the positive integers whose number of divisors is not 2.
Array begins:
2, 1, 1, 1, 1, 1, 1, 1, 1, 1,
3, 4, 2, 2, 2, 2, 2, 2, 2,
4, 6, 3, 3, 3, 3, 3, 3,
5, 8, 5, 4, 4, 4, 4,
6, 9, 6, 5, 5, 5,
7, 10, 7, 7, 6,
8, 12, 8, 9,
9, 14, 10,
10, 15,
11,
CROSSREFS
Columns (1-4): A020725, A018252, A213367, A210994.
Sequence in context: A201927 A238442 A090244 * A258263 A096180 A354265
KEYWORD
nonn,tabl
AUTHOR
Omar E. Pol, Aug 11 2012
STATUS
approved