A161542 m-th composite composite(m) is included iff composite(m) + m is prime.

4, 8, 9, 15, 20, 40, 44, 57, 63, 64, 66, 80, 81, 91, 94, 96, 114, 115, 121, 133, 136, 143, 146, 153, 154, 166, 174, 176, 177, 187, 190, 196, 200, 203, 207, 210, 225, 230, 252, 256, 268, 273, 275, 282, 302, 305, 318, 319, 322, 327, 330, 338, 341, 343, 344, 351

Offset

1,1

Comments

8 is composite (3) and 8+3 = 11 is prime; 9 is composite(4) and 9+4 = 13 is prime.

Links

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

Mathematica

Module[{nn=400, cmps}, cmps=Select[Range[nn], CompositeQ]; Select[Partition[Riffle[ Range[ Length[ cmps]], cmps], 2], PrimeQ[Total[#]]&]][[;; , 2]] (* Harvey P. Dale, Sep 20 2023 *)

Crossrefs

Cf. A002808.

Sequence in context: A329936 A023886 A158337 * A131195 A020217 A370999

Adjacent sequences: A161539 A161540 A161541 * A161543 A161544 A161545

Keyword

nonn

Author

Claudio Meller, Jun 13 2009

Status

approved