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.

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

Links

Table of n, a(n) for n=1..7.

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

Adjacent sequences: A257763 A257764 A257765 * A257767 A257768 A257769

Keyword

base,nonn,fini,full

Author

Pieter Post, May 07 2015

Status

approved