A156900 a(n) = the smallest prime power >= the n-th positive squarefree integer.

1, 2, 3, 5, 7, 7, 11, 11, 13, 16, 16, 17, 19, 23, 23, 23, 27, 29, 31, 31, 37, 37, 37, 37, 41, 41, 41, 43, 43, 47, 47, 53, 53, 59, 59, 59, 59, 61, 64, 67, 67, 67, 71, 71, 71, 73, 79, 79, 79, 79, 83, 83, 89, 89, 89, 89, 97, 97, 97, 97, 97, 101, 103, 103, 107, 107, 107, 109, 113

Offset

1,2

Comments

The first positive squarefree integer is considered to be 1 here.

Links

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

Mathematica

Block[{nn = 110, s}, s = Select[Range[nn], SquareFreeQ]; Map[If[# == 1, 1, SelectFirst[# + Range[0, # - 1], PrimePowerQ]] &, s]] (* Michael De Vlieger, Oct 30 2017 *)

Crossrefs

Cf. A081217, A156898, A156899, A005117, A000961.

Sequence in context: A196365 A195882 A332333 * A039734 A020482 A060308

Adjacent sequences: A156897 A156898 A156899 * A156901 A156902 A156903

Keyword

nonn

Author

Leroy Quet, Feb 17 2009

Extensions

Extended by D. S. McNeil, Mar 23 2009

Status

approved