A379648 a(n) = position of prime(n) in A379652, or a(n) = -1 if prime(n) is not in A379652.

1, 7, 2, 8, 3, 13, 11, 6, 4, 17, 9, 14, 26, 49, 5, 47, 18, 154, 29, 12, 44, 46, 27, 120, 33, 16, 102, 48, 43, 36, 10, 87, 21, 52, 41, 15, 71, 86, 28, 58, 121, 31, 114, 172, 45, 190, 89, 189, 37, 108, 150, 19, 230, 83, 247, 88, 146, 30, 103, 74, 149, 59, 55, 119

Offset

1,2

Links

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

Mathematica

c[_] := True; j = 2; c[2] = False; r = 0; a[1] = PrimePi[j];
Do[m = 2*j + 1;
  While[
    Set[k, SelectFirst[FactorInteger[m][[All, 1]], c]]; ! IntegerQ[k],
    m = 2*m + 1];
  c[k] = False; j = k; a[PrimePi[k]] = n;
  If[k > r, r = k], {n, 2, 256}];
TakeWhile[Array[a, PrimePi[r]], IntegerQ]

Crossrefs

Cf. A379652.

Sequence in context: A201322 A093753 A249506 * A199046 A198564 A259072

Adjacent sequences: A379645 A379646 A379647 * A379649 A379650 A379651

Keyword

nonn,easy

Author

Michael De Vlieger, Jan 01 2025

Status

approved