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 A049030 Sum of sigma(j) for 1<=j<10^n, where sigma(j) = A048050(j) is the sum of the proper divisors >1 of j (excluding 1 and n). 0
 16, 3034, 320243, 32226805, 3224444759, 322465138002, 32246681892518, 3224670122682648, 322467031114802292 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS C. Rivera, Prime Puzzles and Problems Connection FORMULA At a(3) = 320243, for example, take a(3) from A049000: 820741 - 500498 = 320243. Compute 500498 from 999*1000/2 = 499500, split evenly and reverse to 500499 - 1 = 500498. Add a 9 and 0 for each successive term. EXAMPLE For n = 1, the sum of sigma(j), for j < 10 is 0 + 0 + 0 + 2 + 0 + 5 + 0 + 6 + 3 = 16, so a(1) = 16. CROSSREFS Cf. A001065, A048050, A048995. Sequence in context: A221253 A123282 A091160 * A223068 A051551 A289703 Adjacent sequences:  A049027 A049028 A049029 * A049031 A049032 A049033 KEYWORD base,nonn AUTHOR STATUS approved

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Last modified February 19 22:38 EST 2019. Contains 320328 sequences. (Running on oeis4.)