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 A175070 a(n) is the sum of perfect divisors of n - n, where a perfect divisor of n is a divisor d such that d^k = n for some k >= 1. 3
 0, 0, 0, 2, 0, 0, 0, 2, 3, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 3, 0, 0, 0, 0, 2, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS a(1) = 0, for n >=2: a(n) = sum of perfect divisors of n less than n. a(n) > 0 for perfect powers n = A001597(m) for m > 2. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = A175067(n) - n. PROG (PARI) A175070(n) = if(!ispower(n), 0, sumdiv(n, d, if((d>1)&&(d

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Last modified October 23 22:36 EDT 2019. Contains 328377 sequences. (Running on oeis4.)