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 A066468 Numbers having just three anti-divisors. 0
 7, 10, 11, 14, 15, 19, 20, 21, 26, 29, 30, 34, 44, 48, 51, 54, 56, 69, 79, 89, 106, 114, 120, 134, 141, 146, 156, 174, 191, 216, 224, 244, 251, 271, 296, 309, 316, 321, 359, 376, 384, 386, 394, 404, 411, 439, 496, 516, 524, 596, 601, 614, 659, 664, 691, 719 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS See A066272 for definition of anti-divisor. LINKS Table of n, a(n) for n=1..56. 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[ 2*n], OddQ[ # ] && # != 1 &]]] }, # < n & ]]; Select[ Range[10^4], Length[ antid[ # ]] == 3 & ] CROSSREFS Cf. A066272. Sequence in context: A191875 A194418 A094764 * A347393 A088769 A057986 Adjacent sequences: A066465 A066466 A066467 * A066469 A066470 A066471 KEYWORD nonn AUTHOR Robert G. Wilson v, Jan 02 2002 STATUS approved

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Last modified September 16 19:55 EDT 2024. Contains 375977 sequences. (Running on oeis4.)