OFFSET
1,4
COMMENTS
For a prime p: a(p) = 1.
FORMULA
a(n) = n^2 - A007434(n) = n^2 - J_2(n).
G.f.: -Sum_{k>=2} mu(k) * x^k * (1 + x^k) / (1 - x^k)^3. - Ilya Gutkovskiy, Sep 14 2021
MATHEMATICA
Table[a=GroupElements[CyclicGroup[n]]; n^2-Count[Flatten[Table[Table[GroupOrder[PermutationGroup[{a[[i]], a[[j]]}]], {i, 1, n}], {j, 1, n}]], n], {n, 1, 30}] (* Geoffrey Critzer, Apr 14 2013 *)
PROG
(PARI)
A007434(n) = if(n<1, 0, sumdiv(n, d, d^2*moebius(n/d)));
a(n) = n^2 - A007434(n); /* Joerg Arndt, Apr 14 2013 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Sep 24 2001
EXTENSIONS
More terms from Vladeta Jovovic, Sep 25 2001
STATUS
approved