OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
480 is in the sequence since bi-unitary sigma(480) = 1512 > 3 * 480.
MATHEMATICA
f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bsigma[m_] := DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; bAbundantQ[n_] := bsigma[n] > 3 n; Select[Range[1000], bAbundantQ] (* after Michael De Vlieger at A188999 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 01 2017
STATUS
approved