Problem Statement

A   Narcissistic decimal number   is a non-negative integer,

n

{\displaystyle n}

,   that is equal to the sum of the

m

{\displaystyle m}

-th   powers of each of the digits in the decimal representation of

n

{\displaystyle n}

,   where

m

{\displaystyle m}

is the number of digits in the decimal representation of

n

{\displaystyle n}

.

Narcissistic (decimal) numbers are sometimes called   Armstrong   numbers, named after Michael F. Armstrong. They are also known as   Plus Perfect   numbers.

Generate and show here the first   25   narcissistic decimal numbers.

Note:

0

1

= 0

{\displaystyle 0^{1}=0}

,   the first in the series.

Let's start with the solution:

(ns narcissistic.core
  (:require [clojure.math.numeric-tower :as math]))

(defn digits [n] ;; digits of a number.
  (->> n str (map (comp read-string str))))

(defn narcissistic? [n] ;; True if the number is a Narcissistic one.
  (let [d (digits n)
        s (count d)]
    (= n (reduce + (map #(math/expt % s) d)))))

(defn firstNnarc [n] ;;list of the first "n" Narcissistic numbers.
  (take n (filter narcissistic? (range))))