A162213 a(n) = the smallest positive multiple of n with exactly n digits when written in binary.

1, 2, 6, 8, 20, 36, 70, 128, 261, 520, 1034, 2052, 4108, 8204, 16395, 32768, 65552, 131076, 262162, 524300, 1048593, 2097172, 4194326, 8388624, 16777225, 33554456, 67108878, 134217748, 268435484, 536870940, 1073741854, 2147483648

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Formula

a(n) = n * ceiling(2^(n-1)/n). - Alois P. Heinz, Jul 11 2009

Maple

a := proc (n) local k: for k while nops(convert(k*n, base, 2)) <> n do end do; k*n end proc: seq(a(n), n = 1 .. 24); # Emeric Deutsch, Jul 10 2009
a:= n-> n*ceil(2^(n-1)/n): seq(a(n), n=1..40); # Alois P. Heinz, Jul 11 2009

Mathematica

Array[# Ceiling[2^(# - 1)/#] &, 32] (* Michael De Vlieger, Nov 04 2017 *)

Crossrefs

Cf. A162214, A053041.

Sequence in context: A143481 A093968 A064713 * A100358 A134136 A185165

Adjacent sequences: A162210 A162211 A162212 * A162214 A162215 A162216

Keyword

base,nonn,easy

Author

Leroy Quet, Jun 28 2009

Extensions

More terms from Emeric Deutsch and Alois P. Heinz, Jul 11 2009

Status

approved