A257572 Prime root of n-th term in A257278.

2, 2, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 3, 5, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 5, 2, 3, 7, 2, 3, 5, 2, 2, 3, 7, 2, 5, 3, 2, 2, 7, 3, 5, 2, 3, 2, 5, 2, 7, 3, 2, 2, 3, 5, 7, 2, 3, 2, 5, 2, 3, 7, 2, 5, 3, 2, 2, 3, 7, 2, 5, 2, 3, 11, 2, 7, 5, 3, 2, 2, 3

Offset: 1

Author

Reinhard Zumkeller, May 01 2015

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A257278, A020639, A025473, A257573.

Programs

Haskell

a257572 = a020639 . a257278

Mathematica

seq[lim_] := Module[{s = {}, p = 2, r}, While[p^p <= lim, r = Range[p, Log[p, lim]]; AppendTo[s, Transpose[{ConstantArray[p, Length[r]], p^r}]]; p = NextPrime[p]]; SortBy[Flatten[s, 1], Last][[;; , 1]]]; seq[10^13] (* Amiram Eldar, Apr 14 2025 *)

Formula

a(n) = A020639(A257278(n)).

A257278(n) = a(n) ^ A257573(n).

a(n) <= A257573(n) by definition of A257278.