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A298984
Numbers k such that floor((10^p) / k) has digital sum k for some integer p.
0
1, 3, 7, 8, 9, 13, 14, 22, 30, 33, 34, 43, 49, 51, 55, 56, 62, 66, 73, 76, 83, 90, 91, 92, 94, 95, 96, 98, 99, 103, 109, 113, 127, 129, 130, 132, 133, 137, 139, 141, 150, 154, 159, 169, 170, 174, 175, 177, 179, 180, 181, 185, 186, 192, 194, 202, 208, 211, 215
OFFSET
1,2
COMMENTS
This sequence has similarities with A106039: here some partial sum of digits of 1/k equals k, there some partial (cyclical) sum of digits of k equals k.
A052268 is a subsequence.
EXAMPLE
floor(1000 / 7) = 142 and 1 + 4 + 2 = 7, hence 7 belongs to this sequence.
floor(1 / 5) = 0 and floor ((10^p) / 5) = 2 for any p > 0, hence 5 does not belong to this sequence.
PROG
(PARI) is(n) = my (r=1/n, s=0); while (r, s+=floor(r); if (s==n, return (1), s>n, return (0); r = frac(r)*10); return (0)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Rémy Sigrist, Jan 31 2018
STATUS
approved