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 A189558 Least number k>0 such that x' = k has n solutions, where x' is the arithmetic derivative (A003415) of x. 5
 2, 4, 10, 16, 24, 54, 48, 60, 84, 90, 114, 144, 150, 120, 168, 234, 216, 252, 288, 210, 354, 240, 432, 360, 330, 552, 456, 390, 462, 480, 546, 420, 510, 600, 672, 792, 756, 714, 798, 690, 720, 630, 1116, 1026, 930, 780, 870, 960, 900, 924, 1134, 1296, 840 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS It appears that all terms are even. See A189559 for k restricted to prime numbers and A189560 restricted to odd numbers. REFERENCES See A003415. LINKS T. D. Noe and Donovan Johnson, Table of n, a(n) for n = 0..5000 (terms up to a(665) from T. D. Noe) FORMULA a(n) is the least k>0 such that A099302(k) = n. CROSSREFS See A003415, A099302, A189559, A189560. Sequence in context: A096689 A039682 A218665 * A111149 A123689 A137928 Adjacent sequences:  A189555 A189556 A189557 * A189559 A189560 A189561 KEYWORD nonn AUTHOR T. D. Noe, Apr 24 2011 STATUS approved

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Last modified December 4 02:40 EST 2021. Contains 349469 sequences. (Running on oeis4.)