# More and more threes

Algebra Level 4

$3,33,333,\ldots, \underbrace{33333\ldots3}_{n \text{ number of 3's}}$

Given that the sum of the $n$ number of terms above is equal to

$\frac 1a (b^{n+1} - cn - d )$

for positive integers $a,b,c$ and $d$. Find the value of $a+b+c+d+1$.

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