OFFSET
1,6
FORMULA
EXAMPLE
MATHEMATICA
b[n_] := If[n == 1, 1, Product[{p, e} = pe; If[p == 2, 2, ((Floor[p/4] + Floor[Mod[p, 4]/2])*4 + (2 - Mod[p, 4]) I)]^e, {pe, FactorInteger[n]}]];
a[n_] := Im[b[n]];
Array[a, 100] (* Jean-François Alcover, Dec 12 2021 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Reinhard Zumkeller, Oct 08 2002
STATUS
approved