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 A280078 Partial products of A007429 (Sum_{d|n} sigma(d)). 2
 1, 4, 20, 220, 1540, 30800, 277200, 7207200, 129729600, 3632428800, 47221574400, 2597186592000, 38957798880000, 1402480759680000, 49086826588800000, 2797949115561600000, 53161033195670400000, 3827594390088268800000, 80379482191853644800000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS sigma(n) is the sum of the divisors of n (A000203). LINKS Table of n, a(n) for n=1..19. FORMULA a(n) = Product_{i=1..n} A007429(i). PROG (Magma) [&*[&+[SumOfDivisors(d): d in Divisors(k)]: k in [1..n]]: n in [1..100]] CROSSREFS Cf. A000203, A280075 (partial products of A211776), A280077 (partial sums of A007429). Sequence in context: A213144 A215873 A066917 * A032081 A034235 A352412 Adjacent sequences: A280075 A280076 A280077 * A280079 A280080 A280081 KEYWORD nonn AUTHOR Jaroslav Krizek, Dec 25 2016 STATUS approved

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Last modified August 6 15:42 EDT 2024. Contains 374974 sequences. (Running on oeis4.)