-- polynomial utils a `nmul` n = map (*n) a a `ndiv` n = map (`div` n) a instance (Integral a) => Num [a] where (+) = zipWith (+) negate = map negate a * b = foldr f undefined b where f x z = (a `nmul` x) + (0 : z) abs _ = undefined signum _ = undefined fromInteger n = fromInteger n : repeat 0 -- replace x in polynomial with x^n repl a n = concatMap (: replicate (n-1) 0) a -- S2: (a^2 + b)/2 cycleIndexS2 a b = (a*a + b)`ndiv` 2 -- S4: (a^4 + 6 a^2 b + 8 a c + 3 b^2 + 6 d) / 24 cycleIndexS4 a b c d = ((a ^ 4) + (a ^ 2 * b) `nmul` 6 + (a * c) `nmul` 8 + (b ^ 2) `nmul` 3 + d `nmul` 6) `ndiv` 24 a598 = x1 -- A000598: A(x) = 1 + (1/6)*x*(A(x)^3 + 3*A(x)*A(x^2) + 2*A(x^3)) x1 = 1 : ((x1^3) + ((x2*x1)`nmul` 3) + (x3`nmul`2)) `ndiv` 6 x2 = x1`repl`2 x3 = x1`repl`3 x4 = x1`repl`4 -- A000678 = x CycleIndex(S4, A000598(x)) a678 = 0 : cycleIndexS4 x1 x2 x3 x4 -- A000599 = CycleIndex(S2, A000598(x) - 1) a599 = cycleIndexS2 (0 : tail x1) (0 : tail x2) -- A000602 = A000678(x) - A000599(x) + A000599(x^2) a602 = a678 - a599 + x2 main = mapM_ print $ take 200 $ zip [0 ..] a602