It's obvious that the primes which divide the numbers with an odd multiplicity have to be the same. The first times this happens is $72\cdot 98$. $70=2\cdot 5\cdot 7\rightarrow 2, 5, 7$ $71\in\mathbb{P}\rightarrow 71$ $72=2^3\cdot 3^2\rightarrow 2$ $73\in\mathbb{P}\rightarrow 73$ $74=2\cdot 37\rightarrow 2, 37$ $75=3\cdot 5^2\rightarrow 3$ $76=2^2\cdot 19\rightarrow 19$ $77=7\cdot 11\rightarrow 7, 11$ $78=2\cdot 3\cdot 13\rightarrow 2, 3, 13$ $79\in\mathbb{P}\rightarrow 79$ $80=2^4\cdot 5\rightarrow 5$ $81=3^4\rightarrow$ $82=2\cdot 41\rightarrow 2, 41$ $83\in\mathbb{P}\rightarrow 83$ $84=2^2\cdot 3\cdot 7\rightarrow 3, 7$ $85=5\cdot 17\rightarrow 5, 17$ $86=2\cdot 43\rightarrow 2, 43$ $87=3\cdot 29\rightarrow 3, 29$ $88=2^3\cdot 11\rightarrow 2, 11$ $89\in\mathbb{P}\rightarrow 89$ $90=2\cdot 3^2\cdot 5\rightarrow 2, 5$ $91=7\cdot 13\rightarrow 7, 13$ $92=2^2\cdot 23\rightarrow 23$ $93=3\cdot 31\rightarrow 3, 31$ $94=2\cdot 47\rightarrow 2, 47$ $95=5\cdot 19\rightarrow 5, 19$ $96=2^5\cdot 3\rightarrow 2, 3$ $97\in\mathbb{P}\rightarrow 97$ $98=2\cdot 7^2\rightarrow 2$