A361875 Integers of the form k*2^m + 1 where 0 < k <= m and k is odd.

3, 5, 9, 17, 25, 33, 49, 65, 97, 129, 161, 193, 257, 321, 385, 513, 641, 769, 897, 1025, 1281, 1537, 1793, 2049, 2561, 3073, 3585, 4097, 4609, 5121, 6145, 7169, 8193, 9217, 10241, 12289, 14337, 16385, 18433, 20481, 22529, 24577, 28673, 32769, 36865, 40961, 45057, 49153, 57345, 65537, 73729, 81921

Offset

1,1

Comments

Every term is odd.

Links

Table of n, a(n) for n=1..52.

Example

641 = 5*2^7 + 1 is a term because 0 < 5 <= 7 and 5 is odd.

Maple

# Maple program (due to David A. Corneth)
aList := proc(upto)
   local i, j, R:
   R := {}:
   for i from 1 to ilog2(upto) do
      for j from 1 to min(i, floor(upto/2^i)) do
         R := `union`(R, {j*2^i+1}): od: od:
   R: end:
aList(10^12);

Crossrefs

Cf. A361180 (prime terms).

Sequence in context: A032679 A385126 A154607 * A287207 A298338 A018162

Adjacent sequences: A361872 A361873 A361874 * A361876 A361877 A361878

Keyword

nonn,easy

Author

Lorenzo Sauras Altuzarra, Mar 27 2023

Status

approved