A074967 a(n) = least k such that n^n - k is prime.

1, 4, 5, 4, 7, 2, 3, 10, 33, 42, 19, 12, 17, 52, 59, 18, 65, 2, 51, 2, 23, 120, 35, 2, 63, 10, 39, 186, 7, 74, 47, 200, 53, 24, 19, 48, 333, 56, 57, 192, 127, 348, 63, 124, 213, 60, 359, 2, 213, 2, 387, 526, 269, 252, 863, 16, 131, 370, 503, 294, 83, 68, 317

Offset: 2

Author

Zak Seidov, Oct 03 2002

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 2..500

Crossrefs

Cf. A033933, A074966.

Programs

Mathematica

PrimePrevDelta[n_]:=Module[{k},k=n-1;While[ !PrimeQ[k],k-- ];k=n-k]; lst={};Do[AppendTo[lst,PrimePrevDelta[n^n]],{n,2,5!}];lst (* Vladimir Joseph Stephan Orlovsky, Jun 11 2009 *)
lk[n_]:=Module[{nn=n^n},nn-NextPrime[nn,-1]]; Array[lk,70,2] (* Harvey P. Dale, Jan 20 2019 *)

PARI

a(n)=(x->x-precprime(x))(n^n) \\ Charles R Greathouse IV, Nov 25 2014

Extensions

More terms from Robert G. Wilson v, Oct 04 2002

Offset corrected by R. J. Mathar, Jun 12 2009