OFFSET
1,2
COMMENTS
From Torlach Rush, Oct 11 2018: (Start)
For k <= 10^7:
- a(n) is squarefree.
- if a(n) > M(k) then A008683(a(n)) is negative.
- if a(n) = M(k) then A008683(a(n)) is positive. (End)
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)
EXAMPLE
M(31) = -4, smallest one equal to +-4.
MAPLE
with(numtheory): k := 0: s := 0: for n from 1 to 20000 do s := s+mobius(n): if abs(s) > k then k := abs(s): print(n); fi; od:
MATHEMATICA
a = s = 0; Do[s = s + MoebiusMu[n]; If[ Abs[s] > a, a = Abs[s]; Print[n]], {n, 1, 20000}]
PROG
(Haskell)
import Data.List (elemIndex)
import Data.Maybe (fromJust)
a051402 = (+ 1) . fromJust . (`elemIndex` ms) where
ms = map (abs . a002321) [1..]
-- Reinhard Zumkeller, Dec 26 2012
(PARI) M(n)=sum(k=1, n, moebius(k));
print1(1, ", "); c=M(1); n=2; while(n<10^3, if(abs(M(n))>c, print1(n, ", "); c=abs(M(n))); n++) \\ Derek Orr, Jun 14 2016
(PARI) M(n) = sum(k=1, n, moebius(k));
a(n) = my(k = 1, s = moebius(1)); while (abs(s) != n, k++; s += moebius(k)); k; \\ Michel Marcus, Oct 12 2018
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
STATUS
approved