|
Search: id:A103578
|
|
|
| A103578 |
|
Number of divisors of m^2, where m is the smallest number with at least n divisors. |
|
+0
2
|
|
| 1, 3, 5, 9, 15, 15, 21, 21, 25, 27, 45, 45, 63, 63, 63, 63, 75, 75, 81, 81, 105, 105, 105, 105, 135, 135, 135, 135, 135, 135, 189, 189, 225, 225, 225, 225, 243, 243, 243, 243, 315, 315, 315, 315, 315, 315, 315, 315, 405, 405, 405, 405, 405, 405, 405, 405, 405
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
a(n)=A000005((A061799(n))^2). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 01 2008]
|
|
EXAMPLE
|
a(8) = 21 because smallest number with 8 divisors is 24, 24^2 = 576 and 576 has 21 divisors.
|
|
MATHEMATICA
|
a = {}; i = 1; For[n = 1, n < 60, n++, While[DivisorSigma[0, i] < n, i++ ]; AppendTo[a, DivisorSigma[0, i^2]]]; a [From Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 31 2008]
|
|
CROSSREFS
|
Cf. A141264.
Sequence in context: A053993 A071155 A120695 this_sequence A116649 A129771 A093688
Adjacent sequences: A103575 A103576 A103577 this_sequence A103579 A103580 A103581
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 31 2008
|
|
EXTENSIONS
|
Edited by R. J. Mathar, Sep 01 2008, Dec 15 2008
Extended beyond a(8) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 31 2008
|
|
|
Search completed in 0.002 seconds
|
