OFFSET
1,1
COMMENTS
This sequence also contains the term 230361837156847526055247872. - Yasutoshi Kohmoto, May 10 2008
301183421949935616 also belongs to this sequence. - Avinoam Kalma (a.kalma(AT)gmail.com), May 04 2009
22290964134962716779872256 is in this sequence. [From Gerard P. Michon, May 10 2009]
LINKS
G. P. Michon, Table of n, a(n) for n = 1..21
G. P. Michon, Multiperfect and hemiperfect numbers [From Gerard P. Michon, Jun 04 2009]
Walter Nissen, Abundancy : Some Resources
Walter Nissen, Abundancy : Some Resources
EXAMPLE
Sigma(4320)=15120=7*4320/2, so 4320 is in the sequence.
MATHEMATICA
Do[If[DivisorSigma[1, m]==3.5*m, Print[m]], {m, 2*10^8}]
PROG
(PARI) is(n)=sigma(n, -1)==7/2 \\ Charles R Greathouse IV, Mar 09 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jud McCranie, Jun 16 2000
EXTENSIONS
Terms confirmed through a(5) by Ray Chandler, Sep 18 2008
a(6) and a(7) found by Yasutoshi Kohmoto and confirmed by Washington Bomfim, Oct 19 2008
Edited by N. J. A. Sloane, Sep 19 2008, Apr 18 2009
a(8), a(10), a(12) [and above] found by Michel Marcus, added by Gerard P. Michon, Jun 04 2009
STATUS
approved