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

Author

Pieter Post, May 07 2015

Keywords

• base
• nonn
• fini
• full

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

Examples

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

Crossrefs

Cf. A115518.

Programs

Mathematica

Select[Range@1648656,#==Total[IntegerDigits[#]] *Total[IntegerDigits[#]^2]^2&] (* Ivan N. Ianakiev, May 08 2015 *)