A327328 - OEIS

A327328

a(n) is the smallest positive integer divisible by exactly n nonpowers of 2.

1, 3, 6, 12, 18, 45, 30, 105, 72, 60, 90, 315, 120, 3645, 210, 180, 450, 1575, 480, 2835, 360, 420, 630, 3465, 900, 720, 7290, 1620, 840, 14175, 1440, 10395, 1800, 1260, 3150, 1680, 3240, 1937102445, 5670, 14580, 3600, 127575, 3360, 2066715, 2520, 3780, 6930

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OFFSET

0,2

COMMENTS

Terms are of the form A233819(m) * 2^k for some m > 0, k >= 0. - David A. Corneth, Nov 25 2019

LINKS

David A. Corneth, Table of n, a(n) for n = 0..1000

PROG

(PARI) ispp(x) = my(p); (x == 1) || (isprimepower(x, &p) && (p==2));

nbdiv(k) = #select(x->(!ispp(x)), divisors(k));

a(n) = my(k=1); while (nbdiv(k) != n, k++); k; \\ Michel Marcus, Nov 25 2019

(PARI) a(n) = for(i = 1, oo, if(numdiv(i) - valuation(i, 2) - 1 == n, return(i))) \\ David A. Corneth, Nov 25 2019