A093687 Numbers k such that the total number of 1's in the binary expansion of all the divisors of k sets a new record.

1, 2, 3, 6, 12, 18, 24, 30, 60, 90, 120, 180, 252, 360, 420, 504, 540, 630, 756, 840, 1080, 1260, 1980, 2520, 3780, 5040, 6300, 7560, 12600, 13860, 15120, 21420, 25200, 27720, 32760, 41580, 42840, 49140, 55440, 65520, 81900, 83160, 98280, 128520, 138600

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..120

Mathematica

a[n_] := Plus @@ DigitCount[Divisors[n], 2, 1]; am = -1; c = 0; seq={}; Do[a1 = a[n]; If[a1 > am, am = a1; c++; AppendTo[seq, n]], {n, 1, 10^4}]; seq (* Amiram Eldar, Dec 17 2019 *)

Prog

(Python) # uses imports and definitions in A093653
from itertools import count, islice
def f(n): return A093653(n)
def agen(r=0): yield from ((m, r:=fm)[0] for m in count(1) if (fm:=f(m))>r)
print(list(islice(agen(), 45))) # Michael S. Branicky, Feb 15 2023

Crossrefs

Cf. A093653.

Sequence in context: A324177 A280681 A328899 * A000423 A389366 A007335

Adjacent sequences: A093684 A093685 A093686 * A093688 A093689 A093690

Keyword

nonn,base

Author

Jason Earls, May 16 2004

Status

approved