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 A192286 Antiharmonic numbers using anti-divisors: numbers n such that sigma*(n) divides sigma*_2(n), where sigma*(n) is the sum of anti-divisors of n and sigma*_2(n) the sum of squares of anti-divisors of n. 0
 3, 4, 6, 9, 36, 54, 96, 216, 576, 1212, 1296, 1582, 2171, 3129, 3599, 26847, 45914, 69984, 76393, 91013, 137173, 176678, 182559, 183087, 236196, 393216, 497664, 3823898, 28697814, 31850496, 46572031, 47992961, 83951616, 84934656, 95969521, 126310141, 472250381 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA Like A020487 but using anti-divisors. 4, 9, 36, 576, 1296, etc. are antiharmonic both with divisors and anti-divisors. EXAMPLE Anti-divisors of 1212 are 5, 8, 24, 25, 97, 485, 808 and their sum is 1452. The sum of the squares of anti-divisors is 898788 and 898788/1452=619. MAPLE with(numtheory); P:=proc(n) local a, b, i, k; for i from 3 to n do a:=0; b:=0; for k from 2 to i-1 do if abs((i mod k)- k/2) < 1 then a:=a+k; b:=b+k^2; fi; od; if trunc(b/a)=b/a then print(i); fi; od; end: P(200000); CROSSREFS Cf. A020487, A066272. Sequence in context: A350741 A191699 A293272 * A242028 A254002 A095729 Adjacent sequences: A192283 A192284 A192285 * A192287 A192288 A192289 KEYWORD nonn AUTHOR Paolo P. Lava, Jul 28 2011 EXTENSIONS a(22)-a(37) from Donovan Johnson, Sep 22 2011 STATUS approved

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Last modified March 31 21:40 EDT 2023. Contains 361673 sequences. (Running on oeis4.)