Template:Infobox number 155 (one hundred [and] fifty-five) is the natural number following 154 and preceding 156.
In mathematicsEdit
143 is:
- a composite number
- a semiprime.
- a deficient number, since 1+5+31=37<155.
- odious, since its binary expansion <math>10011011_2</math> has a total of 5 ones in it.
There are 143 primitive permutation groups of degree 81. Template:OEIS2C
If one adds up all the primes from the least through the greatest prime factors of 143, that is, 5 and 31, the result is 143. (sequence A055233 in the OEIS) Only three other "small" semiprimes (10, 39, and 371) share this attribute.