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 A230578 Smallest number larger than 1 such that multiplying n-th highly composite number by a(n) will give a highly composite number. 0
 2, 2, 3, 2, 2, 2, 5, 5, 2, 2, 2, 3, 2, 7, 2, 2, 3, 2, 2, 2, 2, 3, 11, 2, 2, 11, 11, 2, 2, 2, 2, 3, 2, 2, 13, 13, 13, 2, 2, 2, 2, 3, 2, 2, 5, 2, 2, 2, 3, 17, 2, 17, 2, 17, 2, 2, 5, 2, 2, 2, 3, 19, 2, 2, 2, 3, 2, 2, 5, 19, 2, 2, 2, 3, 5, 2, 2, 2, 2, 23, 7, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Conjecture: all a(n) are prime numbers. This conjecture is false: a(643) = 6 is not prime. - Alois P. Heinz, Oct 23 2013 LINKS EXAMPLE a(3) cannot be 2 because the third highly composite number, 4, when multiplied by 2, yields 8, which is not a highly composite number. CROSSREFS Cf. A002182. Sequence in context: A329612 A305980 A329601 * A089132 A107259 A121041 Adjacent sequences:  A230575 A230576 A230577 * A230579 A230580 A230581 KEYWORD nonn AUTHOR J. Lowell, Oct 23 2013 EXTENSIONS More terms from Alois P. Heinz, Oct 23 2013 STATUS approved

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Last modified January 20 08:12 EST 2021. Contains 340301 sequences. (Running on oeis4.)