A172155 a(n) = Omega(6*n-1)*Omega(6*n+1).

1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 4, 3, 2, 1, 4, 1, 2, 2, 2, 3, 1, 4, 1, 1, 4, 2, 4, 2, 1, 2, 1, 6, 2, 2, 2, 1, 3, 1, 4, 2, 4, 2, 1, 2, 6, 2, 2, 6, 1, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 4, 1, 6, 1, 2, 2, 2, 3, 1, 2, 6, 2, 2, 2, 2, 2, 2, 4, 1, 4, 4, 3, 2, 4, 2, 2, 1, 3, 4, 2, 3, 1, 3, 2, 1, 8, 2

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 26 2010

Keywords

• nonn

Examples

			For n=1, Omega(6*n-1)*Omega(6*n+1)=Omega(5)*Omega(7)=1, so a(1)=1.
		

Crossrefs

Cf. A145193.

Programs

Maple

A172155 := proc(n) numtheory[bigomega](6*n-1)*numtheory[bigomega](6*n+1) ; end proc: seq(A172155(n),n=1..100) ; # R. J. Mathar, Jan 30 2010

Mathematica

Table[Times@@PrimeOmega[6*n+{1,-1}],{n,120}] (* Harvey P. Dale, Jul 16 2020 *)

Extensions

Corrected by R. J. Mathar, Jan 30 2010