A357677 Powers of either 3 or 5 or 7 (and 0).

0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729, 2187, 2401, 3125, 6561, 15625, 16807, 19683, 59049, 78125, 117649, 177147, 390625, 531441, 823543, 1594323, 1953125, 4782969, 5764801, 9765625, 14348907, 40353607, 43046721, 48828125, 129140163

Offset: 1

Author

Shreevatsa R, Oct 08 2022

Keywords

• nonn
• easy

Comments

Block groups in which copies of the superblock are stored, when the "sparse superblock feature" is enabled, in the ext2/ext3/ext4 filesystems. (That is, copies of the superblock are stored in every block group when the feature is disabled, or in block groups 0, 1, 3, 5, 7, 9, 25, ... when the feature is enabled.)

Links

• The Linux Kernel documentation, The Second Extended Filesystem (ext2)
• The Linux Kernel documentation, ext4 Data Structures and Algorithms
• Unix.StackExchange, Superblock replicas in ext4

Crossrefs

Union of (0 and) A000244, A000351, A000420.

Programs

Mathematica

With[{max = 1.3*10^8}, Sort @ Flatten @ Join[{0, 1}, Table[p^Range[1, Floor[Log[p, max]]], {p, {3, 5, 7}}]]] (* Amiram Eldar, Oct 09 2022 *)