Let the smallest value of \( k \in \mathbb{N} \), for which the coefficient of \( x^3 \) in \( (1+x)^3 + (1+x)^4 + (1+x)^5 + \ldots + (1+x)^{99} + (1+kx)^{100} \), \( x \neq 0 \), is \( \left( \frac{43n + 101}{4} \right)\binom{100}{3} \) for some \( n \in \mathbb{N} \), be \( p \). Then the value of \( p + n \) is: