Post History
#2: Post edited
- The number $4294967295$ has prime factors $3,5,17,257,\text{and }65537$.
- The number is one less than a power of $2$, and its prime factors are all one more than a power of $2$. This made me wonder if this happens for other numbers that are one less than a power of $2$.
- $N$ | $2^{N}-1$ | $\text{Prime factors}$
- --- | --- | ---
- $1$ | $1$ | $-$
- $\boldsymbol{2}$ | $\boldsymbol{3}$ | $\boldsymbol{3}$
- $3$ | $7$ | $7$
- $\boldsymbol{4}$ | $\boldsymbol{15}$ | $\boldsymbol{3,5}$
- $5$ | $31$ | $31$
- $6$ | $63$ | $3,3,7$
- $7$ | $127$ | $127$
- $\boldsymbol{8}$ | $\boldsymbol{255}$ | $\boldsymbol{3,5,17}$
- $9$ | $511$ | $7,73$
- $10$ | $1023$ | $3,11,31$
- $11$ | $2047$ | $23,89$
- $12$ | $4095$ | $3,3,5,7,13$
- $13$ | $8191$ | $8191$
- $14$ | $16383$ | $3,43,127$
- $15$ | $32767$ | $7,31,151$
- $\boldsymbol{16}$ | $\boldsymbol{65535}$ | $\boldsymbol{3,5,17,257}$
It appears that each $N$ that is a power of $2$ gives a $2^N-1$ that has prime factors in a pattern. This pattern continues with the number I first mentioned:- $N$ | $2^{N}-1$ | $\text{Prime factors}$
- --- | --- | ---
- $2$ | $3$ | $3$
- $4$ | $15$ | $3,5$
- $8$ | $255$ | $3,5,17$
- $16$ | $65535$ | $3,5,17,257$
- $32$ | $4294967295$ | $3,5,17,257,65537$
- Does this pattern continue indefinitely?
- The number $4294967295$ has prime factors $3,5,17,257,\text{and }65537$.
- The number is one less than a power of $2$, and its prime factors are all one more than a power of $2$. This made me wonder if this happens for other numbers that are one less than a power of $2$.
- $N$ | $2^{N}-1$ | $\text{Prime factors}$
- --- | --- | ---
- $1$ | $1$ | $-$
- $\boldsymbol{2}$ | $\boldsymbol{3}$ | $\boldsymbol{3}$
- $3$ | $7$ | $7$
- $\boldsymbol{4}$ | $\boldsymbol{15}$ | $\boldsymbol{3,5}$
- $5$ | $31$ | $31$
- $6$ | $63$ | $3,3,7$
- $7$ | $127$ | $127$
- $\boldsymbol{8}$ | $\boldsymbol{255}$ | $\boldsymbol{3,5,17}$
- $9$ | $511$ | $7,73$
- $10$ | $1023$ | $3,11,31$
- $11$ | $2047$ | $23,89$
- $12$ | $4095$ | $3,3,5,7,13$
- $13$ | $8191$ | $8191$
- $14$ | $16383$ | $3,43,127$
- $15$ | $32767$ | $7,31,151$
- $\boldsymbol{16}$ | $\boldsymbol{65535}$ | $\boldsymbol{3,5,17,257}$
- It appears that each $N$ that is a power of $2$ gives a $2^N-1$ that has prime factors in a pattern of numbers one more than a power of $2$. This pattern continues with the number I first mentioned:
- $N$ | $2^{N}-1$ | $\text{Prime factors}$
- --- | --- | ---
- $2$ | $3$ | $3$
- $4$ | $15$ | $3,5$
- $8$ | $255$ | $3,5,17$
- $16$ | $65535$ | $3,5,17,257$
- $32$ | $4294967295$ | $3,5,17,257,65537$
- Does this pattern continue indefinitely?
#1: Initial revision
Prime factor pattern in numbers one less than a power of 2
The number $4294967295$ has prime factors $3,5,17,257,\text{and }65537$. The number is one less than a power of $2$, and its prime factors are all one more than a power of $2$. This made me wonder if this happens for other numbers that are one less than a power of $2$. $N$ | $2^{N}-1$ | $\text{Prime factors}$ --- | --- | --- $1$ | $1$ | $-$ $\boldsymbol{2}$ | $\boldsymbol{3}$ | $\boldsymbol{3}$ $3$ | $7$ | $7$ $\boldsymbol{4}$ | $\boldsymbol{15}$ | $\boldsymbol{3,5}$ $5$ | $31$ | $31$ $6$ | $63$ | $3,3,7$ $7$ | $127$ | $127$ $\boldsymbol{8}$ | $\boldsymbol{255}$ | $\boldsymbol{3,5,17}$ $9$ | $511$ | $7,73$ $10$ | $1023$ | $3,11,31$ $11$ | $2047$ | $23,89$ $12$ | $4095$ | $3,3,5,7,13$ $13$ | $8191$ | $8191$ $14$ | $16383$ | $3,43,127$ $15$ | $32767$ | $7,31,151$ $\boldsymbol{16}$ | $\boldsymbol{65535}$ | $\boldsymbol{3,5,17,257}$ It appears that each $N$ that is a power of $2$ gives a $2^N-1$ that has prime factors in a pattern. This pattern continues with the number I first mentioned: $N$ | $2^{N}-1$ | $\text{Prime factors}$ --- | --- | --- $2$ | $3$ | $3$ $4$ | $15$ | $3,5$ $8$ | $255$ | $3,5,17$ $16$ | $65535$ | $3,5,17,257$ $32$ | $4294967295$ | $3,5,17,257,65537$ Does this pattern continue indefinitely?