OFFSET
1,1
LINKS
M. Buratti and F. Merola, Dihedral Hamiltonian cycle systems of the Cocktail Party Graph, J. Combin. Des. 21 (1) (2013) 1-23, Section 3.
MAPLE
isA000961 := proc(n)
local pf;
if n = 1 then
return true;
end if;
pf := ifactors(n)[2] ;
if nops(pf) > 1 then
false;
else
true;
end if ;
end proc:
A023506 := proc(p)
padic[ordp](p-1, 2) ;
end proc:
isA279229 := proc(n)
local ct2, p, l ;
if type(n, 'even') then
false;
elif isA000961(n) then
false;
else
ct2 := 0 ;
for pf in ifactors(n)[2] do
l := A023506(op(1, pf)) ;
ct2 := ct2+l*op(2, pf) ;
end do:
type(ct2, 'even') ;
end if;
end proc:
for n from 2 to 2000 do
if isA279229(n) then
printf("%d, ", n);
end if;
end do:
MATHEMATICA
A023506[p_] := IntegerExponent[p - 1, 2];
isA279229[n_] := Module[{ct2, l}, Which[EvenQ[n], False, PrimePowerQ[n], False, True, ct2 = 0; Do[l = A023506[pf[[1]]]; ct2 = ct2 + l*pf[[2]], {pf, FactorInteger[n]}]; EvenQ[ct2]]];
Select[Range[2, 400], isA279229] (* Jean-François Alcover, Oct 28 2023, after R. J. Mathar's program *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Jan 04 2017
STATUS
approved