A129767 Interleaved primes and semiprimes.

2, 4, 3, 6, 5, 9, 7, 10, 11, 14, 13, 15, 17, 21, 19, 22, 23, 25, 29, 26, 31, 33, 37, 34, 41, 35, 43, 38, 47, 39, 53, 46, 59, 49, 61, 51, 67, 55, 71, 57, 73, 58, 79, 62, 83, 65, 89, 69, 97, 74, 101, 77, 103, 82, 107, 85, 109, 86, 113, 87, 127, 91, 131, 93, 137, 94, 139, 95, 149

Offset

1,1

Links

Alois P. Heinz, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harvey P. Dale)

Formula

a(2*n-1) = A000040(n), a(2*n) = A001358(n).

Mathematica

Module[{nn=200, pr, sp, len}, pr=Prime[Range[PrimePi[nn]]]; sp=Select[Range[ nn], PrimeOmega[#]==2&]; len=Min[Length[pr], Length[sp]]; Thread[{Take[ pr, len], Take[ sp, len]}]]//Flatten (* Harvey P. Dale, Jun 02 2020 *)

Crossrefs

Cf. A000040, A001358, A037143.

Sequence in context: A281120 A246682 A143691 * A119618 A113321 A271647

Adjacent sequences: A129764 A129765 A129766 * A129768 A129769 A129770

Keyword

easy,less,nonn

Author

Jonathan Vos Post, Jun 02 2007

Status

approved