A063565 Smallest positive number k such that 2^k contains n.

10, 4, 1, 5, 2, 8, 4, 15, 3, 12, 10, 40, 7, 17, 18, 21, 4, 27, 30, 13, 11, 18, 43, 41, 10, 8, 18, 15, 7, 32, 22, 17, 5, 25, 27, 25, 16, 30, 14, 42, 12, 22, 19, 22, 18, 28, 42, 31, 11, 32, 52, 9, 19, 16, 25, 16, 8, 20, 33, 33, 23, 58, 18, 14, 6, 16, 46, 24, 15, 34, 29, 21, 17, 30

Offset: 0

Author

Robert G. Wilson v, Aug 10 2001

Keywords

• base
• nonn

Examples

			a(7) = 15 because 2^15 = 32768.
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..10000
• Popular Computing (Calabasas, CA), Two Tables, Vol. 1, (No. 9, Dec 1973), page PC9-16.

Crossrefs

Apart from initial term, a duplicate of A030000.

Cf. A006889, A131535, A131536, A259089, A063565, A259091, A259092.

Programs

Mathematica

a = {}; Do[k = 1; While[ StringPosition[ ToString[2^k], ToString[n] ] == {}, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

Python

def A063565(n):
    s, k, k2 = str(n), 1, 2
    while True:
        if s in str(k2):
            return k
        k += 1
        k2 *= 2 # Chai Wah Wu, Jun 20 2015

Extensions

More terms from Hans Havermann