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A331619
a(n) is the smallest positive number k such that the decimal expansion of n*2^k contains the string n.
2
1, 4, 4, 7, 4, 9, 4, 8, 4, 10, 10, 10, 10, 10, 10, 10, 10, 7, 10, 10, 4, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 4, 10, 28, 19, 13, 15, 16, 40, 20, 30, 53, 27, 20, 27, 35, 30, 20, 53, 31, 20, 4, 8, 18, 35, 20, 10, 30, 23, 20
OFFSET
0,2
EXAMPLE
n a(n) n*2^a(n)
-- ---- --------
0 1 0
1 4 16
2 4 32
3 7 384
4 4 64
5 9 2560
6 4 96
7 8 1792
8 4 128
9 10 9216
10 10 10240
CROSSREFS
Sequence in context: A197009 A204156 A163106 * A374104 A258972 A146564
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Jan 22 2020
STATUS
approved