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A266531 Square array read by antidiagonals upwards: T(n,k) = n-th number with k odd divisors. 13
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
T(n,k) is also the n-th positive integer with exactly k partitions into consecutive parts. - Omar E. Pol, Aug 16 2018
LINKS
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.
Sequence in context: A335910 A362814 A371152 * A284311 A357581 A174225
KEYWORD
nonn,tabl
AUTHOR
Omar E. Pol, Apr 02 2016
STATUS
approved

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Last modified March 29 08:53 EDT 2024. Contains 371268 sequences. (Running on oeis4.)