A175131 a(n) = 2^(n-1) mod semiprime(n).

1, 2, 4, 8, 2, 2, 1, 18, 6, 18, 1, 8, 1, 22, 4, 16, 23, 2, 14, 2, 52, 2, 49, 2, 10, 65, 64, 8, 44, 2, 64, 2, 42, 12, 62, 56, 31, 98, 81, 50, 74, 2, 1, 128, 96, 71, 60, 7, 81, 16, 94, 146, 1, 144, 108, 154, 133, 4, 46, 153, 67, 44, 88, 90, 198, 32, 14, 117

Offset

1,2

Links

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

Mathematica

Module[{nn=300, sems, len}, sems=Select[Range[nn], PrimeOmega[#]==2&]; len = Length[sems]; PowerMod[2, #[[1]]-1, #[[2]]]&/@Thread[{Range[len], sems}]] (* Harvey P. Dale, May 19 2018 *)

Prog

(PARI) lista(nn) = {semip = select(n->bigomega(n) == 2, vector(nn, i, i)); for (i=1, #semip, print1(2^(i-1) % semip[i], ", "); ); } \\ Michel Marcus, Sep 11 2013

Crossrefs

Cf. A000079, A001358, A175036, A181615.

Sequence in context: A197282 A215452 A362985 * A033921 A167420 A195711

Adjacent sequences: A175128 A175129 A175130 * A175132 A175133 A175134

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Dec 02 2010

Extensions

More terms from Michel Marcus, Sep 11 2013

Status

approved