A033859 Numbers k such that A033831(k) = A034444(k) where A034444(k) = number of unitary divisors of k.

8, 16, 24, 27, 36, 40, 54, 81, 88, 100, 104, 120, 125, 135, 136, 152, 168, 184, 189, 196, 225, 232, 248, 250, 264, 270, 272, 280, 296, 297, 312, 328, 343, 344, 351, 375, 376, 378, 408, 424, 440, 441, 456, 459, 472, 484, 488, 513, 520, 536, 568, 584, 594, 616

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Maple

with(numtheory): for n from 1 to 1200 do it := divisors(n): count := 0: for i from 1 to nops(it) do if it[i]>=3 and 1<=n/it[i] and n/it[i]<=(it[i]-2) then count := count+1 fi:od: if count=2^nops(ifactors(n)[2]) then printf(`%d, `, n) fi; od:

Mathematica

j[n_] := DivisorSum[n, 1&, # > 2 && n/# < #-1 &]; Select[Range[1000], j[#] == 2^PrimeNu[#] &] (* Amiram Eldar, Jun 11 2019 *)

Crossrefs

Cf. A033831, A034444.

Sequence in context: A344653 A345193 A365866 * A177899 A358727 A246311

Adjacent sequences: A033856 A033857 A033858 * A033860 A033861 A033862

Keyword

easy,nonn

Author

Naohiro Nomoto

Extensions

More terms from James A. Sellers, Jun 20 2000

Status

approved