%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