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

1,2

Comments

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

Links

Table of n, a(n) for n=1..49.

Example

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.

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

Crossrefs

Cf. A007632.

Sequence in context: A055978 A356189 A245695 * A356815 A352554 A352563

Adjacent sequences: A069022 A069023 A069024 * A069026 A069027 A069028

Keyword

base,nonn

Author

Amarnath Murthy, Apr 02 2002

Extensions

Edited by Robert G. Wilson v, Nov 05 2002

Status

approved