LFSR's are mind blowing; the fact that you can generate a randomish sequence that covers an entire ^2 range visiting each number once, and only once, seems like

LFSR's are mind blowing; the fact that you can generate a randomish sequence that covers an entire ^2 range visiting each number once, and only once, seems like a lucky piece of magic. And in just a couple of lines, excuse my quickie untested code: #include <stdio.h> #include <stdint.h> // 5-bit maximal LSFR taps to get pseudo-random sequence of 31 unique numbers in range 1-31 // 0x12, 0x14, 0x17, 0x1B, 0x1D, 0x1E, 0x18, 0x17 int main(int c, char **v) { uint8_t taps = 0x17; // could be any of the taps above uint8_t seed = 0x7; // start, could be 1-31 uint8_t lfsr = seed; do { printf("%d\n", lfsr); lfsr = (lfsr & 1) ? (lfsr >> 1) ^ taps : (lfsr >> 1); } while ( lfsr != seed ); return 0; }