Claims

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1979_06_01_haight: Haight (Mathematika 1979) proves that for every c some n has sigma(n) > cn while its divisors above one are not the moduli of any covering system; accepted on the refereed publication and the site's credit.

2005_07_18_filaseta_ford_konyagin_pomerance_yu: Theorem 1 of Filaseta, Ford, Konyagin, Pomerance and Yu (J. Amer. Math. Soc. 2007) gives infinitely many H with sigma(H)/H about sqrt(log log H) whose divisors above one support no covering system; accepted as refereed.

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