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A327328
a(n) is the smallest positive integer divisible by exactly n nonpowers of 2.
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
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
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
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Sep 20 2019
EXTENSIONS
a(13)-a(36), a(38)-a(46) from Jon E. Schoenfield, Nov 22 2019
a(37) from Jon E. Schoenfield and David A. Corneth, Nov 25 2019
STATUS
approved