A390306 Numbers > 0 whose binary indices have strictly decreasing first differences.

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 16, 17, 18, 20, 24, 25, 26, 32, 33, 34, 36, 40, 41, 48, 49, 50, 52, 64, 65, 66, 68, 72, 80, 81, 82, 96, 97, 98, 100, 104, 105, 128, 129, 130, 132, 136, 144, 145, 160, 161, 162, 164, 192, 193, 194, 196, 200, 208, 209, 210

Offset

1,2

Comments

A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793.

Links

Table of n, a(n) for n=1..61.

Example

The prime indices of 840 are (4,7,9,10), with first differences (3,2,1), so 840 is in the sequence.

Mathematica

bpe[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
Select[Range[100], Greater@@Differences[bpe[#]]&]

Crossrefs

The opposite for prime indices is A325456, counted by A240027.

For prime indices we have A325457, counted by A320470.

The 0-prepended version is A333255, opposite A333256.

Indicates strictly decreasing rows of A390090.

The opposite version is A390305.

Cf. A000120, A029931, A048793, A070211, A070939, A119387, A124768, A295235, A325545, A325546, A358133, A390091.

Sequence in context: A228897 A068095 A395852 * A064390 A229461 A230709

Adjacent sequences: A390303 A390304 A390305 * A390307 A390308 A390309

Keyword

nonn

Author

Gus Wiseman, Nov 20 2025

Status

approved