A388418 a(n) is the least k such that prime(n)^prime(n) - k is prime.

1, 4, 4, 2, 42, 12, 18, 2, 120, 186, 74, 48, 192, 348, 60, 526, 370, 294, 204, 322, 132, 330, 126, 336, 248, 412, 590, 64, 1406, 282, 672, 90, 250, 378, 712, 80, 138, 1236, 514, 256, 60, 32, 390, 1644, 1684, 2538, 612, 150, 1212, 3276, 616, 2286, 4824, 124, 690, 1284

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..206

Maple

f:= proc(n) local p, t;
 p:= ithprime(n); t:= p^p;
 t - prevprime(t)
end proc:
map(f, [$1..70]); # Robert Israel, Mar 20 2026

Mathematica

a[n_]:=Module[{k=1}, While[!PrimeQ[Prime[n]^Prime[n]-k], k++]; k]; Array[a, 56] (* James C. McMahon, Sep 19 2025 *)

Prog

(PARI) a388418(n) = my(p=prime(n)^prime(n), k=0); until(ispseudoprime(p-k), k++); k

Crossrefs

Cf. A051674, A388417.

Sequence in context: A320147 A369410 A272364 * A188657 A021697 A276635

Adjacent sequences: A388415 A388416 A388417 * A388419 A388420 A388421

Keyword

nonn

Author

Hugo Pfoertner, Sep 18 2025

Status

approved