A066474 Numbers having exactly eight anti-divisors.

85, 98, 112, 113, 200, 256, 265, 312, 364, 400, 420, 441, 481, 484, 544, 625, 729, 761, 800, 924, 925, 1152, 1200, 1444, 1681, 1764, 1849, 1860, 1861, 1936, 2116, 2209, 2245, 2664, 3364, 3481, 3721, 3844, 4704, 5101, 5304, 5476, 5724, 6400, 6889, 7321

Offset

1,1

Comments

See A066272 for definition of anti-divisor.

Links

Table of n, a(n) for n=1..46.

Jon Perry, The Anti-Divisor

Jon Perry, The Anti-divisor [Cached copy]

Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]

Mathematica

antid[n_] := Select[ Union[ Join[ Select[ Divisors[2n - 1], OddQ[ # ] && # != 1 & ], Select[ Divisors[2n + 1], OddQ[ # ] && # != 1 & ], 2n/Select[ Divisors[ 2n], OddQ[ # ] && # != 1 &]]], # < n & ]; Select[ Range[10^4], Length[ antid[ # ]] == 8 & ]

Crossrefs

Cf. A066272.

Sequence in context: A095593 A039487 A157469 * A161479 A027453 A259219

Adjacent sequences: A066471 A066472 A066473 * A066475 A066476 A066477

Keyword

nonn

Author

Robert G. Wilson v, Jan 02 2002

Status

approved