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1980 AMC 12 Question 25

AMC12 · 1980 AMC 12

Question 25

In the nondecreasing sequence of odd integers $$
\begin{aligned} (a_1,a_2,a_3,\ldots) ={}&(1,3,3,3,\\ &5,5,5,5,5,\ldots) \end{aligned}
$$ each positive odd integer $k$ appears $k$ times. It is a fact that there are integers $b,$ $c,$ and $d$ such that, for all positive integers $n,$ $$
a_n=b\left\lfloor\sqrt{n+c}\right\rfloor+d,
$$ where $\lfloor x\rfloor$ denotes the largest integer not exceeding $x.$ The sum $b+c+d$ equals
  1. $0$
  2. $1$
  3. $2$
  4. $3$
  5. $4$