login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A192488 Numbers that set records for number of divisors of n(n-1). 1
2, 3, 4, 6, 9, 15, 16, 21, 36, 64, 81, 100, 105, 196, 225, 385, 441, 561, 936, 1225, 1540, 2016, 2080, 5265, 5985, 12376, 21736, 41041, 78625, 123201, 126225, 156520, 176176, 201825, 313600, 338625, 395200, 453376, 638001, 1154440, 1890945, 2203201, 2697696, 2756160, 4921840, 6969600 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Places of records in A092517.

Bases for which it is easy to find divisibility rules for many numbers in those bases; in base 64 the final digit rule works for 1,2,4,8,16,32,64 and the add the digits rule works for 1,3,7,9,21,63.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..61

EXAMPLE

6 qualifies because 6*5=30 has 8 divisors, more than any smaller number of the form n(n-1).

PROG

(PARI) r=0; t1=1; for(n=2, 1e8, t2=numdiv(n); if(t1*t2>r, r=t1*t2; print1(n", ")); t1=t2) \\ Charles R Greathouse IV, Jul 03 2011

CROSSREFS

Sequence in context: A173278 A173289 A096824 * A089797 A081237 A022159

Adjacent sequences:  A192485 A192486 A192487 * A192489 A192490 A192491

KEYWORD

nonn

AUTHOR

J. Lowell, Jul 02 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 14:51 EST 2020. Contains 338906 sequences. (Running on oeis4.)