A298984 - OEIS

%I #10 Nov 24 2024 03:27:10

%S 1,3,7,8,9,13,14,22,30,33,34,43,49,51,55,56,62,66,73,76,83,90,91,92,

%T 94,95,96,98,99,103,109,113,127,129,130,132,133,137,139,141,150,154,

%U 159,169,170,174,175,177,179,180,181,185,186,192,194,202,208,211,215

%N Numbers k such that floor((10^p) / k) has digital sum k for some integer p.

%C 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.

%C A052268 is a subsequence.

%e floor(1000 / 7) = 142 and 1 + 4 + 2 = 7, hence 7 belongs to this sequence.

%e floor(1 / 5) = 0 and floor ((10^p) / 5) = 2 for any p > 0, hence 5 does not belong to this sequence.

%o (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)

%Y Cf. A007953, A052268, A106039.

%K nonn,base,easy

%O 1,2

%A _Rémy Sigrist_, Jan 31 2018