|
Search: id:A049439
|
|
|
| A049439 |
|
Numbers n such that the number of odd divisors of n is an odd divisor of n. |
|
+0
9
|
|
| 1, 2, 4, 8, 9, 16, 18, 32, 36, 64, 72, 128, 144, 225, 256, 288, 441, 450, 512, 576, 625, 882, 900, 1024, 1089, 1152, 1250, 1521, 1764, 1800, 2025, 2048, 2178, 2304, 2500, 2601, 3042, 3249, 3528, 3600, 4050, 4096, 4356, 4608, 4761, 5000, 5202, 5625, 6084
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Invented by the HR concept formation program.
a(n) = A000079(k)*A016754(m) for appropriate k, m. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 05 2008
|
|
LINKS
|
R. Zumkeller, Table of n, a(n) for n = 1..1000
S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.
S. Colton, HR - Automatic Theory Formation in Pure Mathematics
|
|
EXAMPLE
|
There are 3 odd divisors of 18, namely 1,3 and 9 and 3 itself is an odd divisor of 9.
|
|
CROSSREFS
|
Contains A000079 and A033950, Cf. A036896.
Sequence in context: A080025 A152111 A025611 this_sequence A079931 A055008 A046678
Adjacent sequences: A049436 A049437 A049438 this_sequence A049440 A049441 A049442
|
|
KEYWORD
|
nice,nonn
|
|
AUTHOR
|
Simon Colton (simonco(AT)cs.york.ac.uk)
|
|
|
Search completed in 0.002 seconds
|
