-3,1

a(n) = Min[T in A014612 and A002321(T) = n].

a(-3) = 20 = 2^2 * 5 = the first 3-almost prime T for which the Mertens function M(T) = -3.

a(-2) = 8 = 2^3 = the first 3-almost prime T for which the Mertens function M(T) = -2.

a(-1) = 27 = 3^3 = the first 3-almost prime T for which the Mertens function M(T) = -1.

a(0) = 164 = 2^2 * 41 = Min[A014612 INTERSECTION A028442] = the first semiprime T for which the Mertens function M(T) = 0.

a(1) = 98 = 2 * 7^2 = Min[A014612 INTERSECTION A118684] = the first 3-almost prime T for which the Mertens function M(s) = 1.

a(2) = 335 = 3 * 5 * 23 = the first 3-almost prime T for which the Mertens function M(T) = 2.

a(3) = 343 = 7^3 = the first 3-almost prime T for which the Mertens function M(T) = 3.

isA014612 := proc(n) option remember ; RETURN( numtheory[bigomega](n) = 3) ; end: A008683 := proc(n) option remember ; numtheory[mobius](n) ; end: A002321 := proc(n) option remember ; add(A008683(k), k=1..n) ; end: A123174 := proc(n) local T; for T from 2 do if isA014612(T) then if A002321(T) = n then RETURN(T) ; fi; fi; od: end: for n from -3 to 30 do printf("%d, ", A123174(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 27 2009]

Cf. A014612, A002321, A028442, A118684.

Sequence in context: A108967 A097395 A097390 this_sequence A040384 A078080 A136010

Adjacent sequences: A123171 A123172 A123173 this_sequence A123175 A123176 A123177

easy,nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 02 2006

Replaced a(2)=335 by 345 and extended to a(30). R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 27 2009