3003

Number
$3003$ (three thousand and three) is:


 * $3 \times 7 \times 11 \times 13$


 * The $77$th triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $2211$, $2278$, $2346$, $2415$, $2485$, $2556$, $2628$, $2701$, $2775$, $2850$, $2926$:
 * $3003 = \displaystyle \sum_{k \mathop = 1}^{77} k = \dfrac {77 \times \left({77 + 1}\right)} 2$


 * The $10$th palindromic triangular number after $0$, $1$, $3$, $6$, $55$, $66$, $171$, $595$, $666$.


 * The $39$th hexagonal number after $1$, $6$, $15$, $28$, $45$, $66$, $91$, $\ldots$, $2145$, $2278$, $2415$, $2556$, $2701$, $2850$:
 * $3003 = \displaystyle \sum_{k \mathop = 1}^{39} \left({4 k - 3}\right) = 39 \left({2 \times 39 - 1}\right)$


 * The $6$th palindromic triangular number after $0$, $1$, $3$, $6$, $66$ whose index is itself palindromic:
 * $3003 = T_{77}$


 * The only known integer to appear as many as $8$ times in Pascal's triangle:
 * $3003 = \dbinom {3003} 1 = \dbinom {78} 2 = \dbinom {15} 5 = \dbinom {14} 6 = \dbinom {14} 8 = \dbinom {15} {10} = \dbinom {78} {76} = \dbinom {3003} {3002}$

Also see

 * Numbers Appearing 8 Times in Pascal's Triangle