day3-.clj

(defn day3* [input]
  (loop [i 2 mem [1 1]]
    (let [[x y] (coords i)
          v (apply + (for [p [-1 0 1] q [-1 0 1]
                           :let [f (offset (+ x p) (+ y q))]
                           :when (< f i)]
                       (get mem f)))]
      (if (> v input)
        v
        (recur (inc i) (conj mem v))))))