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A257766 Numbers n such that the sum of the digits of n times the square of the sum of the digits squared of n equals n. 2

%I

%S 1,2023,2400,52215,615627,938600,1648656

%N Numbers n such that the sum of the digits of n times the square of the sum of the digits squared of n equals n.

%C Sequence is finite since it cannot contain numbers of 9 or more digits. Indeed a number of 9 digits is at least equal to 10^8, but the function computed here for a number of n digits is at most (9*n)*(9^2*n)^2, which for n=9 is 43046721 < 10^8. - _Giovanni Resta_, May 08 2015

%e 52215 is in the sequence because 52215 = (5+2+2+1+5)*(5^2+2^2+2^2+1^2+5^2)^2.

%t Select[Range@1648656,#==Total[IntegerDigits[#]] *Total[IntegerDigits[#]^2]^2&] (* _Ivan N. Ianakiev_, May 08 2015 *)

%Y Cf. A115518.

%K base,nonn,fini,full

%O 1,2

%A _Pieter Post_, May 07 2015

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Last modified September 26 03:40 EDT 2022. Contains 356986 sequences. (Running on oeis4.)