155
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Number
$155$ (one hundred and fifty-five) is:
- $5 \times 31$
- The $10$th second pentagonal number after $2$, $7$, $15$, $26$, $40$, $57$, $77$, $100$, $126$:
- $155 = \dfrac {10 \left({3 \times 10 + 1}\right)} 2$
- The $20$th generalized pentagonal number after $1$, $2$, $5$, $7$, $12$, $15$, $22$, $26$, $35$, $40$, $51$, $57$, $70$, $77$, $92$, $100$, $117$, $126$, $145$:
- $155 = \dfrac {10 \left({3 \times 10 + 1}\right)} 2$
- The $31$st positive integer $n$ such that no factorial of an integer can end with $n$ zeroes.
- The $59$th (strictly) positive integer after $1$, $2$, $3$, $\ldots$, $95$, $96$, $102$, $108$, $114$, $119$, $120$, $125$, $143$ which cannot be expressed as the sum of distinct primes of the form $6 n - 1$