Are A055999 and A074171 somehow the same?

[Alonso Del Arte]

I was wondering if there was anything interesting to the difference
between triangular numbers and multiples of 3, I calculated the first
few nonnegative terms and put that into the Lookup and A055999 and
A074171 came up as results. These two sequences appear identical,
apart from A074171's two intial terms.

A055999 is a(n)=n*(n+7)/2, which works out to be ((n^2 - n)/2) - 3n
with a different offset. A074171 is Start with 1, add the next number
if one gets a prime then subtract the next number else add the next. I
entered the two sequences into Mathematica, omitting the first two
terms of A074171, then asked A055999 == A074171 and it answered True.

So the question I have now is: has anyone else noticed this and if so
have they been able to determine whether this is just a huge
coincidence because they've found that the two sequences diverge at a
larger n or do the two sequences agree for as far as has been checked?

Alonso del Arte