OFFSET
1,1
COMMENTS
a(12) <= 4440632687496. - Donovan Johnson, Mar 31 2013
From Daniel Suteu, May 24 2022: (Start)
a(12) <= 2571228006912,
a(13) <= 85266458294400,
a(14) <= 4638227848902900,
a(15) <= 209103527633041800,
a(16) <= 10931190635671518600,
a(17) <= 545209768960172964900,
a(18) <= 34893425213451069753600,
a(19) <= 2000640771807316185690000. (End)
FORMULA
a(n) <= A153076(n), for n >= 2. - Daniel Suteu, May 24 2022
EXAMPLE
a(9) = 81239400; sigma(81239400) = 300690390 = 2*3*5*7*11*13*17*19*31 (9 distinct prime factors).
PROG
(PARI) v=vector(9); for(m=2, 81239400, n=omega(sigma(m)); if(v[n]==0, v[n]=m; print(n " " v[n]))) /* Donovan Johnson, Mar 31 2013 */
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Donovan Johnson, Dec 09 2008
STATUS
approved