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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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column k lists the numbers j such that A000005(j) <> k.

LINKS

Table of n, a(n) for n=1..80.

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 A324336

Adjacent sequences:  A210973 A210974 A210975 * A210977 A210978 A210979

KEYWORD

nonn,tabl

AUTHOR

Omar E. Pol, Aug 11 2012

STATUS

approved

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Last modified April 23 07:51 EDT 2019. Contains 322381 sequences. (Running on oeis4.)