A351623 Numbers k where 3k sets a record for the number of divisors of multiples of 3.
1, 2, 4, 8, 12, 16, 20, 40, 60, 80, 120, 240, 280, 420, 560, 840, 1680, 2520, 3360, 5040, 6720, 8400, 9240, 15120, 16800, 18480, 27720, 36960, 55440, 73920, 92400, 110880, 166320, 184800, 221760, 240240, 360360, 480480, 720720, 960960, 1201200, 1441440, 2162160, 2402400
Offset: 1
Keywords
Examples
6 is not in the sequence because 3*6=18 and 3*4=12 each have 6 divisors. 8 is in the sequence because 3*8=24 sets a record for the number of divisors of multiples of 3.
Programs
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PARI
lista(nn) = {my(m=0, nm); for (n=1, nn, if ((nm=numdiv(3*n)) > m, m = nm; print1(n, ", ")););} \\ Michel Marcus, May 04 2022
Formula
For n > 1, a(n) = A002182(n+2)/3.
Extensions
More terms from Michel Marcus, May 04 2022
Comments