A066153 (product of digits of n) * (sum of digits of n) = 4n.

0, 4, 18, 45, 864

Offset

1,2

Comments

A d-digit number is at least 10^(d-1), its product of digits is at most 9^d, and its sum of digits is at most 9d. For d >= 70, 4 * 10^(d-1) > 9^d * 9d, and so the sequence is finite. (Of course this can be improved.)

Links

Table of n, a(n) for n=1..5.

Mathematica

Do[ If[ 4n == Apply[ Times, IntegerDigits[n]] Apply[ Plus, IntegerDigits[n]], Print[n]], {n, 0, 10^7} ]

Crossrefs

Sequence in context: A278046 A258634 A280599 * A213926 A023650 A254950

Adjacent sequences: A066150 A066151 A066152 * A066154 A066155 A066156

Keyword

nonn,base,fini

Author

Robert G. Wilson v, Dec 13 2001

Extensions

OFFSET changed from 0,2 to 1,2 by Harry J. Smith, Feb 03 2010

Status

approved