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 A234516 Composite numbers n sorted by decreasing values of alpha(n) = log_n(sigma(n)) - log_n(n+1), where sigma(n) = A000203(n) = the sum of divisors of n. 12
 12, 6, 24, 36, 18, 30, 60, 8, 4, 48, 20, 72, 120, 84, 16, 42, 10, 40, 180, 90, 96, 144, 240, 168, 108, 360, 28, 54, 420, 252, 132, 80, 216, 210, 32, 126, 300, 336, 480, 56, 192, 288, 720, 840, 66, 504, 156, 540, 150, 264, 14, 600, 140, 270, 1260, 432, 78, 1080 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The number alpha(n)  = log_n(sigma(n)) - log_n(n+1) = log_n[sigma(n) / (n+1)] is called the alpha-deviation from primality of number n; alpha(p) = 0 for p = prime. See A234520 for definition of beta(n). Lim_n->infinity alpha(n) = 0. Conjecture: Every composite number n has a unique value of alpha(n). Conjecture: sequence A234517 is not the sequence of numbers from a(n) such that a(n) > a(k) for all k < n. LINKS Jaroslav Krizek, Table of n, a(n) for n = 1..200 EXAMPLE For the number 12; alpha(12) = log_12(sigma(12)) - log_12(12+1) = log_12(28) - log_12(13) = 0.308766187… = A234518 (maximal value of function alpha(n)). PROG (PARI) lista(nn) = {v = vector(nn, n, if ((n==1) || isprime(n), 0, log(sigma(n)/(n+1))/log(n))); v = vecsort(v, , 5); for (i=1, 80, print1(v[i], ", ")); } \\ Michel Marcus, Dec 10 2014 CROSSREFS Cf. A234515, A234517, A234518, A234519, A234520, A234521, A234522, A234523, A234524. Sequence in context: A040135 A004015 A119870 * A177690 A038332 A093763 Adjacent sequences:  A234513 A234514 A234515 * A234517 A234518 A234519 KEYWORD nonn AUTHOR Jaroslav Krizek, Jan 03 2014 STATUS approved

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Last modified July 8 04:16 EDT 2020. Contains 335504 sequences. (Running on oeis4.)