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 A318877 Sum of divisors d of n for which 2*phi(d) < d. 3
 0, 0, 0, 0, 0, 6, 0, 0, 0, 10, 0, 18, 0, 14, 0, 0, 0, 24, 0, 30, 0, 22, 0, 42, 0, 26, 0, 42, 0, 46, 0, 0, 0, 34, 0, 72, 0, 38, 0, 70, 0, 62, 0, 66, 0, 46, 0, 90, 0, 60, 0, 78, 0, 78, 0, 98, 0, 58, 0, 138, 0, 62, 0, 0, 0, 94, 0, 102, 0, 94, 0, 168, 0, 74, 0, 114, 0, 110, 0, 150, 0, 82, 0, 186, 0, 86, 0, 154, 0, 154, 0, 138, 0, 94, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = Sum_{d|n} [2*phi(d) < d]*d, where [ ] are the Iverson brackets. For all n >= 1, a(n) + A318876(n) + 2*(A006519(n)-1) = A000203(n). PROG (PARI) A318877(n) = sumdiv(n, d, ((2*eulerphi(d))

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Last modified August 2 01:19 EDT 2021. Contains 346408 sequences. (Running on oeis4.)