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 A211780 a(n) = Sum_{d_
 0, 2, 2, 7, 2, 14, 2, 18, 9, 18, 2, 43, 2, 22, 20, 41, 2, 54, 2, 57, 24, 30, 2, 106, 13, 34, 31, 71, 2, 110, 2, 88, 32, 42, 28, 162, 2, 46, 36, 142, 2, 138, 2, 99, 81, 54, 2, 237, 17, 102, 44, 113, 2, 178, 36, 178, 48, 66, 2, 325, 2, 70, 99, 183, 40, 194, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that n divides a(n) are given in A068978. LINKS Antti Karttunen, Table of n, a(n) for n = 1..27144 (first 1000 terms from Jaroslav Krizek) FORMULA a(n) = A007429(n) - n = A211779(n) + A000203(n) - n . a(n) = (Sum_{d|n} A000203(d)) - n. - Antti Karttunen, Nov 13 2017 EXAMPLE For n = 12: Sum_{d_

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Last modified January 28 00:32 EST 2020. Contains 331313 sequences. (Running on oeis4.)