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A266531 Square array read by antidiagonals upwards: T(n,k) = n-th number with k odd divisors. 9
1, 2, 3, 4, 5, 9, 8, 6, 18, 15, 16, 7, 25, 21, 81, 32, 10, 36, 27, 162, 45, 64, 11, 49, 30, 324, 63, 729, 128, 12, 50, 33, 625, 75, 1458, 105, 256, 13, 72, 35, 648, 90, 2916, 135, 225, 512, 14, 98, 39, 1250, 99, 5832, 165, 441, 405, 1024, 17, 100, 42, 1296, 117, 11664, 189, 450, 567, 59049, 2048, 19, 121, 51, 2401, 126, 15625 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

T(n,k) is the n-th positive integer with exactly k odd divisors.

This is a permutation of the natural numbers.

T(n,k) is also the n-th number j with the property that the symmetric representation of sigma(j) has k subparts (cf. A279387). - Omar E. Pol, Dec 27 2016

LINKS

Table of n, a(n) for n=1..73.

Index entries for sequences that are permutations of the natural numbers

EXAMPLE

The corner of the square array begins:

1,    3,  9, 15,   81,  45,   729, 105,  225,  405...

2,    5, 18, 21,  162,  63,  1458, 135,  441,  567...

4,    6, 25, 27,  324,  75,  2916, 165,  450,  810...

8,    7, 36, 30,  625,  90,  5832, 189,  882,  891...

16,  10, 49, 33,  648,  99, 11664, 195,  900, 1053...

32,  11, 50, 35, 1250, 117, 15625, 210, 1089, 1134...

64,  12, 72, 39, 1296, 126, 23328, 231, 1225, 1377...

128, 13, 98, 42, 2401, 147, 31250, 255, 1521, 1539...

...

CROSSREFS

Row 1 is A038547.

Column 1-10: A000079, A038550, A072502, apparently A131651, A267696, A230577, A267697, A267891, A267892, A267893.

Cf. A001227, A182469, A236104, A237591, A237593, A240062, A261697, A261698, A261699, A279387.

Sequence in context: A092975 A164340 A046021 * A284311 A174225 A182945

Adjacent sequences:  A266528 A266529 A266530 * A266532 A266533 A266534

KEYWORD

nonn,tabl

AUTHOR

Omar E. Pol, Apr 02 2016

STATUS

approved

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Last modified December 13 19:20 EST 2017. Contains 295976 sequences.