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A123174 a(n) is the least triprime T for which the Mertens function M(T) = n. 1
20, 8, 27, 164, 98, 345, 343, 222, 555, 590, 1358, 1388, 1394, 1407, 1406, 1419, 3435, 3231, 3237, 3236, 3245, 3243, 3275, 3282, 3292, 3297, 8163, 8361, 8666, 8662, 8494, 8493, 8538, 8590 (list; graph; refs; listen; history; text; internal format)
OFFSET

-3,1

LINKS

Table of n, a(n) for n=-3..30.

FORMULA

a(n) = min{T in A014612 and A002321(T) = n}.

EXAMPLE

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

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

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

a(0) = 164 = 2^2 * 41 = min{A014612 INTERSECTION A028442} = the first triprime T for which the Mertens function M(T) = 0.

a(1) = 98 = 2 * 7^2 = min{A014612 INTERSECTION A118684} = the first triprime T for which the Mertens function M(T) = 1.

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

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

MAPLE

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: # R. J. Mathar, Jan 27 2009

CROSSREFS

Cf. A002321, A014612, A028442, A118684.

Sequence in context: A097395 A108967 A097390 * A040384 A078080 A216289

Adjacent sequences:  A123171 A123172 A123173 * A123175 A123176 A123177

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Oct 02 2006

EXTENSIONS

a(2)=335 replaced with 345 and sequence extended to a(30) by R. J. Mathar, Jan 27 2009

STATUS

approved

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Last modified February 21 23:41 EST 2020. Contains 332113 sequences. (Running on oeis4.)