A379050 a(n) = b(b(n)), where b(k) = A121053(k).

1, 3, 5, 7, 2, 11, 13, 19, 23, 17, 37, 41, 29, 53, 67, 31, 73, 89, 43, 103, 107, 47, 127, 139, 59, 163, 61, 167, 71, 191, 197, 211, 79, 229, 83, 241, 97, 263, 283, 101, 307, 313, 109, 331, 347, 113, 353, 401, 131, 419, 137, 439, 149, 443, 479, 151, 487, 157, 509, 541, 173, 563, 577, 179, 601, 181, 607, 643, 193, 647, 199, 661, 673, 727, 223, 761, 227, 787, 233, 797, 821, 239

Offset: 1

Author

N. J. A. Sloane, Dec 14 2024

Keywords

• nonn

Comments

Suggested by the formula a(a(n)) = 2*n + 3 for the analogous sequence A079000.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A079000, A121053.

Programs

Mathematica

nn = 2^8; a[1] = 2; u = 4; v = {1}; w = {2}; p = 3;
Do[If[MemberQ[w, n], k = p;
  w = Append[DeleteCases[w, n], p]; p = NextPrime[p],
  If[Length[v] == 0,
    k = u; AppendTo[w, u],
    k = First[v]; v = Rest[v]]];
  Set[{a[n]}, {k}];
  If[n + 1 >= u, u++; While[PrimeQ[u], u++]], {n, 2, nn}];
{1}~Join~TakeWhile[Array[a[a[#]] &, nn], IntegerQ] (* Michael De Vlieger, Dec 17 2024 *)