A215739 Even and odd composite squarefree numbers, interlaced.

6, 15, 10, 21, 14, 33, 22, 35, 26, 39, 30, 51, 34, 55, 38, 57, 42, 65, 46, 69, 58, 77, 62, 85, 66, 87, 70, 91, 74, 93, 78, 95, 82, 105, 86, 111, 94, 115, 102, 119, 106, 123, 110, 129, 114, 133, 118, 141, 122, 143, 130, 145, 134, 155, 138, 159, 142, 161, 146, 165

Offset: 1

Author

Zak Seidov, Aug 22 2012

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A120944.

Programs

Mathematica

Module[{nn=200,csfn,od,ev,len},csfn=Select[Range[nn],CompositeQ[ #] && SquareFreeQ[ #]&];od=Select[csfn,OddQ];ev=Select[csfn,EvenQ];len=Min[ Length[ od],Length[ev]];Riffle[Take[ev,len],Take[od,len]]] (* Harvey P. Dale, Nov 20 2022 *)

Formula

For k=1,2,.., a(2k-1)=A039956(k+1), a(2k)=A024556(k); A039956 Even squarefree numbers, A024556 Odd squarefree composite numbers.