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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.
6
1, 2023, 2400, 52215, 615627, 938600, 1648656
OFFSET
1,2
COMMENTS
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
EXAMPLE
52215 is in the sequence because 52215 = (5+2+2+1+5)*(5^2+2^2+2^2+1^2+5^2)^2.
MATHEMATICA
Select[Range@1648656, #==Total[IntegerDigits[#]] *Total[IntegerDigits[#]^2]^2&] (* Ivan N. Ianakiev, May 08 2015 *)
CROSSREFS
Cf. A115518.
Sequence in context: A119423 A176913 A013687 * A359839 A126821 A333057
KEYWORD
base,nonn,fini,full
AUTHOR
Pieter Post, May 07 2015
STATUS
approved