A072823 Numbers that are not the sum of two powers of 2.

1, 7, 11, 13, 14, 15, 19, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 67, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 97

Offset

1,2

Comments

1 and integers with three or more 1-bits in their binary expansion. - Vladimir Baltic, Jul 23 2002

A073267(a(n)) = 0. [Reinhard Zumkeller, Mar 07 2012]

Appears to be the numbers k >1 for which there exist an x and y (x>y) such that x OR y = k, x+y != k, and x<k. - Gary Detlefs, Jun 02 2014

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Maple

f:= x -> convert(convert(x, base, 2), `+`)>2:
{1} union select(f, {$2..1000}); # Robert Israel, Jun 08 2014

Mathematica

Join[{1}, Select[Range[100], DigitCount[#, 2, 1] >= 3&]] (* Jean-François Alcover, Mar 08 2019 *)

Prog

(Haskell)
a072823 n = a072823_list !! (n-1)
a072823_list = tail $ elemIndices 0 a073267_list
-- Reinhard Zumkeller, Mar 07 2012

Crossrefs

Cf. A048645, A000027.

Sequence in context: A275516 A084451 A091901 * A110547 A279622 A247819

Adjacent sequences: A072820 A072821 A072822 * A072824 A072825 A072826

Keyword

nonn

Author

Jeremy Gardiner, Jul 21 2002

Status

approved