%I #6 Dec 08 2018 17:19:33
%S 13,79,251,619,1291,2399,4093,6553,9973,14639,20731,28559,38393,50599,
%T 65521,83497,104971,130307,159979,194479,234239,279823,331769,390581,
%U 456959,531383,614639,707279,809993,923513,1048573,1185907,1336333
%N Largest prime < n^4.
%t PrimePrev[n_]:=Module[{k},k=n-1;While[ !PrimeQ[k],k-- ];k];f[n_]:=n^4;lst={};Do[AppendTo[lst,PrimePrev[f[n]]],{n,5!}];lst
%t NextPrime[Range[2,40]^4,-1] (* _Harvey P. Dale_, May 05 2018 *)
%Y Cf. A014220, A053001, A077037
%K nonn
%O 2,1
%A _Vladimir Joseph Stephan Orlovsky_, Feb 25 2010