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A270537 Numbers that are equal to their number of digits multiplied by the sum the cubes of the digits. 0

%I

%S 1,2080,2376,2580,3784

%N Numbers that are equal to their number of digits multiplied by the sum the cubes of the digits.

%e 2080 is a term because 2080 = 4 * (2^3 + 0^3 + 8^3 + 0^3);

%e 2376 is a term because 2376 = 4 * (2^3 + 3^3 + 7^3 + 6^3).

%t Position[ Table[ IntegerLength[ k] Sum[( Floor[k/10^n] - 10 Floor[k/10^(n + 1)])^3, {n, 0, IntegerLength@ k}] - k, {k, 1, 10^6}], 0]

%t Select[Range[10^5],With[{id=IntegerDigits[#]},#==Length[id]*Plus@@(id^3)]&] (* _Ray Chandler_, Apr 01 2016 *)

%o (PARI) isok(n) = my(d=digits(n)); n == #d*sum(k=1, #d, d[k]^3); \\ _Michel Marcus_, Mar 25 2016

%K nonn,base,fini,full

%O 1,2

%A _José de Jesús Camacho Medina_, Mar 18 2016

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Last modified August 8 21:43 EDT 2022. Contains 356016 sequences. (Running on oeis4.)