A106137 N-th semiprime mod n.

0, 0, 0, 2, 4, 3, 0, 6, 7, 6, 0, 10, 9, 10, 9, 14, 15, 15, 17, 17, 16, 18, 19, 21, 24, 25, 1, 1, 28, 27, 29, 29, 28, 27, 1, 3, 4, 4, 2, 1, 40, 39, 0, 1, 44, 3, 1, 47, 47, 46, 2, 2, 0, 53, 1, 1, 6, 4, 6, 5, 4, 8, 12, 10, 8, 7, 5, 5, 6, 4, 2, 1, 72, 71, 71, 74, 4, 3, 10, 9, 10, 8, 10, 10, 10, 9

Offset

1,4

Links

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

Example

a(5) = 5th semiprime mod 5 = 14 mod 5 = 4.

Mathematica

Module[{nn=400, sp}, sp=Select[Range[nn], PrimeOmega[#]==2&]; Mod[#[[1]], #[[2]]]&/@ Thread[{sp, Range[Length[sp]]}]] (* Harvey P. Dale, Jun 13 2020 *)

Crossrefs

Cf. A001358.

Sequence in context: A201911 A048644 A246713 * A213381 A127651 A019641

Adjacent sequences: A106134 A106135 A106136 * A106138 A106139 A106140

Keyword

nonn

Author

Shyam Sunder Gupta, May 07 2005

Status

approved