OFFSET
1,5
COMMENTS
Lambda is the function in A002322.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
FORMULA
EXAMPLE
a(13) = 4 because lambda(13) = 12 and the 4 even divisors are { 2, 4, 6, 12}.
MATHEMATICA
f[n_] := Block[{d = Divisors[CarmichaelLambda[n]]}, Count[EvenQ[d], True]]; Table[f[n], {n, 80}]
(* Second program: *)
Array[DivisorSum[CarmichaelLambda@ #, 1 &, EvenQ] &, 105] (* Michael De Vlieger, Dec 04 2017 *)
PROG
(PARI) a(n) = sumdiv(lcm(znstar(n)[2]), d, 1-(d%2)); \\ Michel Marcus, Mar 18 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 22 2011
EXTENSIONS
More terms from Antti Karttunen, Dec 04 2017
STATUS
approved