A118728 a(n) = smallest squarefree number not less than a(n-1)+a(n-2), a(1)=1, a(0)=0.

0, 1, 2, 3, 5, 10, 15, 26, 41, 67, 109, 177, 286, 463, 749, 1213, 1963, 3178, 5141, 8319, 13461, 21781, 35242, 57023, 92265, 149289, 241554, 390845, 632399, 1023245, 1655645, 2678890, 4334537, 7013427, 11347966, 18361393, 29709359

Offset: 0

Author

Reinhard Zumkeller, May 21 2006

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A000045, A005117.

Programs

Mathematica

Module[{lst={0,1}},Do[Module[{k=Total[Take[lst,-2]]}, While[!SquareFreeQ[ k], k++];AppendTo[lst,k]],{40}];Join[{0},Drop[lst,2]]] (* Harvey P. Dale, May 16 2012 *)
ssn[{a_,b_}]:=Module[{k=a+b},While[!SquareFreeQ[k],k++];k]; Join[{0},Drop[NestList[ {#[[2]],ssn[#]}&,{0,1},40][[;;,1]],2]] (* Harvey P. Dale, Aug 12 2024 *)

Formula

a(n) = A067535*(a(n-2)+a(n-1)) for n>1.