|
Search: id:A065301
|
|
|
| A065301 |
|
Both n and the sum of its divisors are square-free numbers. |
|
+0
4
|
|
| 1, 2, 5, 13, 26, 29, 37, 41, 61, 73, 74, 101, 109, 113, 122, 137, 146, 157, 173, 181, 193, 218, 229, 257, 277, 281, 313, 314, 317, 353, 362, 373, 386, 389, 397, 401, 409, 421, 433, 457, 458, 461, 509, 541, 554, 569, 601, 613, 617, 626, 641, 653, 661, 673, 677
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
Harry J. Smith, Table of n, a(n) for n=1,...,1000
|
|
EXAMPLE
|
n=13 and sigma[13]=2.7=14;
n=26 and sigma[26]=1+2+13+26=42=2.3.7.
n = 277 prime, sigma[n] = 278 = 2*139 is square-free.
|
|
PROGRAM
|
(PARI) { n=0; for (m = 1, 10^9, if (abs(moebius(m))==1 && abs(moebius(sigma(m)))==1, write("b065301.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 15 2009]
|
|
CROSSREFS
|
Cf. A000203, A008683, A065299, A065300.
Cf. A065303, A087248, A087249.
Sequence in context: A048871 A072921 A087250 this_sequence A126656 A026522 A122491
Adjacent sequences: A065298 A065299 A065300 this_sequence A065302 A065303 A065304
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Oct 29 2001
|
|
|
Search completed in 0.002 seconds
|
