|
|
A165497
|
|
a(n) starts arithmetic progression of n terms separated by tau(a(n)), each term having the same number of divisors
|
|
2
|
|
|
1, 3, 3, 60, 60, 201, 481, 5989, 3122037, 4434429, 13576837, 183894465, 187925171, 209072257, 1498642520, 12239200420, 20220712468, 20220712468, 875023683404, 992997544772, 2721798771116, 9770941874212, 9770941874212
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
a(15) > 10^9.
a(19) > 10^11. - Donovan Johnson, Sep 24 2009
a(24) > 10^13. - Giovanni Resta, Aug 02 2013
|
|
LINKS
|
Table of n, a(n) for n=1..23.
|
|
EXAMPLE
|
tau(60) = tau(72) = tau(84) = tau(96) = tau(108) = 12. This is the first such progression of length greater than 3, so a(4) and a(5) are both 60.
|
|
PROG
|
(PARI) has(n)=my(t=numdiv(n), s=1); while(numdiv(n+=t)==t, s++); s
a(n)=my(k); while(has(k++)<n, ); k \\ Charles R Greathouse IV, Apr 24 2015
|
|
CROSSREFS
|
Cf. A064491, A165498, A165499.
Sequence in context: A339758 A100065 A066807 * A051752 A332786 A102065
Adjacent sequences: A165494 A165495 A165496 * A165498 A165499 A165500
|
|
KEYWORD
|
hard,nonn,more
|
|
AUTHOR
|
Hugo van der Sanden, Sep 21 2009
|
|
EXTENSIONS
|
a(15)-a(18) from Donovan Johnson, Sep 24 2009
a(19)-a(23) from Giovanni Resta, Aug 02 2013
|
|
STATUS
|
approved
|
|
|
|