|
| |
|
|
A059269
|
|
Number of divisors d(n) is divisible by 3.
|
|
3
| |
|
|
4, 9, 12, 18, 20, 25, 28, 32, 36, 44, 45, 49, 50, 52, 60, 63, 68, 72, 75, 76, 84, 90, 92, 96, 98, 99, 100, 108, 116, 117, 121, 124, 126, 132, 140, 144, 147, 148, 150, 153, 156, 160, 164, 169, 171, 172, 175, 180, 188, 196, 198, 200, 204, 207, 212, 220, 224, 225, 228
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,1
|
|
|
COMMENTS
| d(n) is divisible by 3 iff at least one prime in the prime factorization of n has exponent of the form 3*m + 2. This sequence is an extension of the sequence A038109 in which the numbers has at least one prime with exponent 2 (the case of m = 0 here ) in their prime factorization.
|
|
|
EXAMPLE
| a(7) = 28 because the number of divisors of 28 d(28) = 6
|
|
|
MAPLE
| with(numtheory): for n from 1 to 1000 do if tau(n) mod 3 = 0 then printf(`%d, `, n) fi: od:
|
|
|
CROSSREFS
| A038109, A000005.
Sequence in context: A190448 A089910 A177880 * A081619 A038109 A067259
Adjacent sequences: A059266 A059267 A059268 * A059270 A059271 A059272
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| Avi Peretz (njk(AT)netvision.net.il), Jan 24 2001
|
|
|
EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jan 24 2001
|
| |
|
|
