module _45

let triPentHex =
    let limit = 100000
    let opDict (op : int -> bigint) =
        [1..limit]
        |> Seq.map (fun n -> (op n, n))
        |> dict
    
    let p = opDict common.pentagonalNumber
    let h = opDict common.hexagonalNumber

    common.allIntegers 
    |> Seq.skip 284
    |> Seq.map (fun i -> (common.triangleNumber i, i))
    |> Seq.filter (fst >> (fun t -> p.ContainsKey(t) && h.ContainsKey(t)))
    |> Seq.map (fun t -> (snd t, p.Item(fst t), h.Item(fst t), fst t))
    |> Seq.take 2