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

1,1

Links

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

Formula

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

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 *)

Crossrefs

Cf. A120944.

Sequence in context: A202749 A123623 A240990 * A161397 A145257 A245200

Adjacent sequences: A215736 A215737 A215738 * A215740 A215741 A215742

Keyword

nonn

Author

Zak Seidov, Aug 22 2012

Status

approved