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A192488 Numbers that set records for number of divisors of n(n-1). 1

%I #16 Mar 05 2015 07:46:07

%S 2,3,4,6,9,15,16,21,36,64,81,100,105,196,225,385,441,561,936,1225,

%T 1540,2016,2080,5265,5985,12376,21736,41041,78625,123201,126225,

%U 156520,176176,201825,313600,338625,395200,453376,638001,1154440,1890945,2203201,2697696,2756160,4921840,6969600

%N Numbers that set records for number of divisors of n(n-1).

%C Places of records in A092517.

%C 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.

%H Charles R Greathouse IV, <a href="/A192488/b192488.txt">Table of n, a(n) for n = 1..61</a>

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

%o (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

%K nonn

%O 1,1

%A _J. Lowell_, Jul 02 2011

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)