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 A158661 Least number k such that sigma_n(k) > sigma_n(k+1), where sigma_n(k) = sum of the n-th powers of the divisors of k. 0
 4, 4, 6, 24, 60, 144, 360, 852, 1968, 4488, 10068, 22272, 48780, 105948, 228588, 490404, 1046976, 2225964, 4715400, 9956976, 20965212, 44031360, 92262348, 192920784, 402629256, 838827576, 1744784388, 3623814864, 7516104564 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS It appears that the inequality a(n+1) > (2+2/n)*a(n) is true for n > 4. LINKS FORMULA For n>0, a(n) = A098475(n) - 1. EXAMPLE The values of the sigma_3 function (A001158) are increasing up to 25. Hence a(3)=24. MATHEMATICA Join[{4, 4}, Table[k=Floor[NSolve[Zeta[n](x-1)^n==x^n, x, WorkingPrecision->100][[ -1, 1, 2]]]; While[DivisorSigma[n, k]

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Last modified December 3 05:05 EST 2021. Contains 349445 sequences. (Running on oeis4.)