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 A280817 a(n) = A049501(sigma(n)). 1
 0, 0, 1, 0, 2, 2, 1, 0, 2, 5, 2, 3, 3, 2, 2, 0, 5, 1, 4, 9, 1, 5, 2, 4, 0, 9, 4, 3, 4, 5, 1, 0, 2, 7, 2, 5, 6, 4, 3, 11, 9, 2, 5, 9, 7, 5, 2, 5, 3, 6, 5, 8, 7, 4, 5, 4, 4, 11, 4, 9, 5, 2, 6, 0, 9, 5, 6, 6, 2, 5, 5, 2, 11, 9, 5, 7, 2, 9, 4, 13, 4, 6, 9, 3, 7, 7, 4, 11, 11, 15, 3, 9, 1, 5, 4, 6, 8, 9, 7, 7, 8, 7, 6, 13, 2, 11, 7, 7, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS a(n) = major index (1st definition) of the sum of the divisors of n, i.e., sigma(n). LINKS Indranil Ghosh, Table of n, a(n) for n = 1..10000 Indranil Ghosh, Python Program to generate the sequence FORMULA a(n) = A049501(A000203(n)). EXAMPLE For n = 10, sigma(n) = 18 and major index (1st definition) of 18 is 5. So, a(10) = 5. MATHEMATICA Table[Total@ Flatten@ Position[Partition[IntegerDigits[DivisorSigma[1, n], 2], 2, 1], {1, 0}], {n, 120}] (* Michael De Vlieger, Jan 10 2017, after Harvey P. Dale at A049501 *) CROSSREFS Cf. A049501, A000203, A280726, A280800. Sequence in context: A092869 A029337 A326280 * A060086 A308680 A177975 Adjacent sequences:  A280814 A280815 A280816 * A280818 A280819 A280820 KEYWORD nonn AUTHOR Indranil Ghosh, Jan 08 2017 STATUS approved

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Last modified April 15 10:27 EDT 2021. Contains 342977 sequences. (Running on oeis4.)