511 is the natural number following 510 and preceding 512.
In mathematics It is a Mersenne number, being one less than a power of 2: 511 = 2 9 − 1 {\displaystyle 511=2^{9}-1} . As a result, 511 is a palindromic number and a repdigit in base 2 (1111111112). It is also palindromic and a repdigit in base 8 (7778). It is a generalized heptagonal number (sequence A085787 in the OEIS), since
511 = 1 2 ( 5 n 2 − 3 n ) {\displaystyle 511={\frac {1}{2}}(5n^{2}-3n)} when n = − 14 {\displaystyle n=-14} . It is a Harshad number in bases 3, 5, 7, 10, 13 and 15.
Special use in computers The octal representation of 511 (7778) is commonly used by Unix commands to specify a custom record separator in order to "slurp" input as a whole, rather than line-by-line (i.e. separated at newline characters).
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