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 A071147 Smallest squarefree number k with exactly n prime factors such that the sum of the prime factors is divisible by the largest prime dividing k, or 0 if no such k exists. 8
 1, 2, 0, 30, 3135, 3570, 72930, 1231230, 14804790, 497668710, 14908423530, 278196808890, 12192694624110, 550939666387110, 21275256232500270, 1458502323630662310, 87988283090327810190, 3254611619240885033130, 261462818462495728868790, 9965666894849284108299810, 557940830126698960967415390, 90544636506979071680577724410 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS No solution exists for n=2, so a(2)=0. LINKS Table of n, a(n) for n=0..21. FORMULA A008472(k)/A006530(k) is an integer; k is squarefree and has exactly n prime factors. EXAMPLE a(0) = 1 = 1; a(1) = 2 = 2; a(3) = 30 = 2 * 3 * 5; a(4) = 3135 = 3 * 5 * 11 * 19; a(5) = 3570 = 2 * 3 * 5 * 7 * 17; a(6) = 72930 = 2 * 3 * 5 * 11 * 13 * 17; a(7) = 1231230 = 2 * 3 * 5 * 7 * 11 * 13 * 41. CROSSREFS Cf. A008472, A006530, A000961, A025475, A037074, A071139-A071146. Sequence in context: A340534 A104466 A086487 * A156481 A176726 A156452 Adjacent sequences: A071144 A071145 A071146 * A071148 A071149 A071150 KEYWORD nonn AUTHOR Labos Elemer, May 13 2002 EXTENSIONS Corrected and extended by Donovan Johnson, Apr 22 2008 Name corrected by Jon E. Schoenfield, Jul 08 2018 STATUS approved

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Last modified December 7 14:54 EST 2023. Contains 367657 sequences. (Running on oeis4.)