A331619 - OEIS

%I #5 Jan 22 2020 12:57:28

%S 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,

%T 10,10,10,10,10,10,10,10,10,10,10,10,10,10,4,10,28,19,13,15,16,40,20,

%U 30,53,27,20,27,35,30,20,53,31,20,4,8,18,35,20,10,30,23,20

%N a(n) is the smallest positive number k such that the decimal expansion of n*2^k contains the string n.

%H Rémy Sigrist, <a href="/A331619/a331619.gp.txt">PARI program for A331619</a>

%e   n   a(n)  n*2^a(n)

%e   --  ----  --------

%e    0     1         0

%e    1     4        16

%e    2     4        32

%e    3     7       384

%e    4     4        64

%e    5     9      2560

%e    6     4        96

%e    7     8      1792

%e    8     4       128

%e    9    10      9216

%e   10    10     10240

%Y Cf. A030000, A331440.

%K nonn,base

%O 0,2

%A _Rémy Sigrist_, Jan 22 2020