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 A192269 Super anti-abundant numbers. 1
 1, 3, 4, 5, 7, 13, 17, 32, 38, 45, 67, 77, 143, 203, 247, 473, 682, 787, 1463, 2678, 2992, 3465, 8662, 10868, 16065, 25987, 26163, 29452, 112613, 157658, 202702, 233415, 363825, 795217, 1148647, 1914412, 2139637, 5743237, 5743238, 8393963, 11869357, 64353712 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Like A004394 but using anti-divisors. A super anti-abundant number is a number n such that sigma*(n)/n > sigma*(k)/k for all k sigma*(1)/1 = 0/1 = 0; 3 -> sigma*(3)/3 = 2/3 = 0.6666...; 4 -> sigma*(4)/4 = 3/4 = 0.75; 5 -> sigma*(5)/5 = 5/5 = 1; 7 -> sigma*(7)/7 = 10/7 = 1.4285...; etc. MAPLE with(numtheory); P:= proc(n) local a, k, i, j, s; s:=0; print(1); for i from 3 to n do k:=0; j:=i; while j mod 2 <> 1 do k:=k+1; j:=j/2; od; a:=sigma(2*i+1)+sigma(2*i-1)+sigma(i/2^k)*2^(k+1)-6*i-2; if a/i>s then s:=a/i; print(i); fi; od; end: P(50000); CROSSREFS Cf. A004394, A066417, A192268. Sequence in context: A190213 A216574 A216561 * A284618 A101759 A089560 Adjacent sequences:  A192266 A192267 A192268 * A192270 A192271 A192272 KEYWORD nonn AUTHOR Paolo P. Lava, Jun 28 2011 EXTENSIONS a(26)-a(42) from Donovan Johnson, Sep 07 2011 STATUS approved

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Last modified April 19 18:37 EDT 2019. Contains 322290 sequences. (Running on oeis4.)