A073248 Squarefree numbers k such that k+1 is also squarefree, but k-1 and k+2 are not.

10, 46, 61, 73, 82, 118, 122, 133, 145, 154, 173, 190, 205, 226, 246, 262, 273, 277, 290, 298, 313, 326, 334, 370, 373, 385, 406, 421, 426, 442, 457, 473, 478, 493, 505, 514, 526, 537, 565, 573, 586, 601, 606, 622, 626, 658, 673, 694, 709, 730, 733, 745

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

state:= [true, true, true, true]:
R:= NULL: count:= 0:
for n from 1 while count < 100 do
  state:= [state[2], state[3], state[4], numtheory:-issqrfree(n)];
  if state = [false, true, true, false] then
     R:= R, n-2; count:= count+1
  fi
od:
R; # Robert Israel, Mar 02 2022

Mathematica

Transpose[SequencePosition[Table[If[SquareFreeQ[n], 1, 0], {n, 800}], {0, 1, 1, 0}]][[1]]+1 (* The program uses the SequencePosition function from Mathematica version 10 *) (* Harvey P. Dale, Mar 09 2016 *)

Crossrefs

Cf. A005117, A073250, A073247, A007675.

Sequence in context: A264414 A188699 A044112 * A044493 A350319 A279092

Adjacent sequences: A073245 A073246 A073247 * A073249 A073250 A073251

Keyword

nonn

Author

Reinhard Zumkeller, Jul 22 2002

Status

approved