I suppose it is not equal to one if it is over Reals:
Asymptotics`ClassicLimit[Sin[Pi*Sqrt[n^2 + n]]^2, n -> Infinity]
prints Interval[{0, 1}]. While
Asymptotics`ClassicLimit[Sin[Pi*Sqrt[n^2 + n]]^2, n -> Infinity,
Assumptions -> n \[Element] Integers]
does indeed print one. That is what versions 11.2 and below were using.
I suppose that is like one of those examples in DiscreteLimit[] documentation, after all "integers only" is far from the same as "all reals" limit.
(We cannot use modern Limit to solve this, since it does not allow any Assume[] or Assumptions if it is on the variable we are limiting.)
Edit:
In 13.2 it finally works!
DiscreteLimit[Sin[Pi*Sqrt[n^2 + n]]^2, n -> Infinity]
prints 1.
Sqrt[n^2+n]
is growing asymptotically liken+1/2
. SeeLimit[Sqrt[n^2+n]-n,n->Infinity]
giving1/2
. Thus we can pull the limit into the sine squared and get asymptoticallySin[Pi*(n+1/2)]^2
giving one, as seen numerically too. Did I do something wrong? Btw. although it does not give a result here,DiscreteLimit
is Mathematicas function for Limits over integers. $\endgroup$DiscreteLimit
does not produce this answer. $\endgroup$