|
| |
|
|
A036896
|
|
Odd refactorable numbers.
|
|
8
| |
|
|
1, 9, 225, 441, 625, 1089, 1521, 2025, 2601, 3249, 4761, 5625, 6561, 7569, 8649, 12321, 15129, 16641, 19881, 25281, 31329, 33489, 35721, 40401, 45369, 47961, 50625, 56169, 62001, 71289, 84681, 91809, 95481, 99225, 103041, 106929, 114921
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
COMMENTS
| Odd refactorable numbers are always squares.
All terms = 1 (mod 8). [From Zak Seidov (zakseidov(AT)yahoo.com), May 25 2010]
|
|
|
LINKS
| S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.
S. Colton, HR - Automatic Theory Formation in Pure Mathematics
Harvey P. Dale, Table of n, a(n) for n = 0..1000
|
|
|
EXAMPLE
| 9 is refactorable because tau(9)=3 and 3 divides 9.
|
|
|
MATHEMATICA
| Do[If[IntegerQ[n/DivisorSigma[0, n]], Print[n]], {n, 1, 100000, 2}]
Select[Range[1, 1001, 2]^2, Divisible[#, DivisorSigma[0, #]]&] (* From Harvey P. Dale, Jan 22 2012 *)
|
|
|
CROSSREFS
| Cf. A033950.
Sequence in context: A205568 A033632 A110260 * A120319 A057530 A014736
Adjacent sequences: A036893 A036894 A036895 * A036897 A036898 A036899
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Simon Colton (simonco(AT)cs.york.ac.uk)
|
| |
|
|
