A224987 - OEIS

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A224987

Numbers such that Liouville's function (A002819) and the little omega analog to Liouville's function (A174863) are equal.

1, 2, 3, 20, 21, 22, 23, 24, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 13092, 13093, 13094, 13095, 13096, 13097, 13098, 13099, 13100, 13101, 13102, 13103, 13104, 13105, 13106, 13107, 13232, 13233, 13234, 13235, 13239, 13240, 13241, 13242

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Numbers n such that A002819(n) = A174863(n). There are 9056 terms <= 10^12 (the largest is 16959554). For n from 16959555 to 10^12, A002819(n) < A174863(n).

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..9056

EXAMPLE

n = 43:

A002819(n) = sum_{k = 1..n} (-1)^bigomega(k) = -3.

A174863(n) = sum_{k = 1..n} (-1)^omega(k) = -3.

A002819(43) = A174863(43) = -3.

MATHEMATICA

PrimeOmega[n_] := Plus @@ FactorInteger[n][[All, 2]]; PrimeNu[n_] := Length[FactorInteger[n]]; Reap[For[s1 = 0; s2 = 0; n = 1, n < 15000, n++, s1 = s1 + (-1)^PrimeOmega[n]; s2 = s2 + (-1)^PrimeNu[n]; If[s1 == s2, Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, May 03 2013, after Pari *)

PROG

(PARI) s1=0; s2=0; c=0; for(n=1, 16959554, s1=s1+(-1)^bigomega(n); s2=s2+(-1)^omega(n); if(s1==s2, c++; write("b224987.txt", c " " n)))

CROSSREFS

Cf. A001221, A001222, A008836, A002819, A174863.

Sequence in context: A364648 A089181 A028425 * A024630 A032809 A279180

Adjacent sequences: A224984 A224985 A224986 * A224988 A224989 A224990

KEYWORD

nonn

AUTHOR

Donovan Johnson, Apr 22 2013

STATUS

approved