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A336580
Numbers k such that A334676(k) = 1.
2
1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15, 24, 25, 35, 36, 45, 48, 72, 75, 125, 135, 140, 144, 175, 216, 225, 250, 270, 280, 288, 375, 384, 432, 540, 625, 675, 864, 875, 1080, 1125, 1250, 1296, 1350, 1575, 1620, 1680, 1728, 1750, 1800, 1875, 1944, 2160, 2250, 2500
OFFSET
1,2
COMMENTS
All terms are 7-smooth (A002473).
This sequence is infinite as it contains the powers of 5.
EXAMPLE
Regarding the number 540:
- 540 / 4 = 135,
- 135 / 3 = 45,
- 45 / 5 = 9,
- 9 / 9 = 1,
- so A334676(540) = 1
- and 540 belongs to this sequence.
PROG
(PARI) for (n=1, #keep=vector(2500, n, n==1), if (keep[n], print1 (n ", "); for (d=2, min(9, #keep\n), if (setsearch (Set(digits(nd=n*d)), d), keep[nd]=1))))
(PARI) See Links section.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Jul 26 2020
STATUS
approved