A069025 Smallest power of 2 with digital sum (A007953) n, or 0 if no such number exists.

1, 2, 0, 4, 32, 0, 16, 8, 0, 64, 128, 0, 256, 2048, 0, 0, 0, 0, 4096, 8192, 0, 16384, 0, 0, 65536, 32768, 0, 0, 524288, 0, 1048576, 0, 0, 0, 134217728, 0, 16777216, 0, 0, 67108864, 8388608, 0, 268435456, 0, 0, 4398046511104, 2147483648, 0, 0

Offset: 1

Author

Amarnath Murthy, Apr 02 2002

Keywords

• base
• nonn

Comments

a(3k)=0. In general about half the entries are nonzero.

Examples

			Both 2^4=16 and 2^10=1024 have a digital sum of 7 but 2^4 is the smaller so it is the one presented.
		

Crossrefs

Cf. A007632.

Programs

Mathematica

a = Table[0, {50}]; Do[b = Plus @@ IntegerDigits[2^n]; If[b < 51 && a[[b]] == 0, a[[b]] = 2^n], {n, 0, 10^4}]; a

Extensions

Edited by Robert G. Wilson v, Nov 05 2002