A085445 Numbers equal to exactly twice the sum of the products of each of their digits.

0, 50, 162, 392, 648

Offset

1,2

Comments

Take a number n, create a table with d columns and rows where d=number of digits of n. Each column corresponds to a digit of n and each row to a digit of n. In each cell, multiply the two digits of n represented by that row and column. Add up the sums of all of the rows and all of the columns to get n again.

Actually, the "sum of the products of the digits" is simply the square of the sum of digits. Sequence is complete. - Giovanni Resta, Mar 21 2013

Links

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

Example

162 = 2*(1*1 + 1*6 + 1*2 + 6*1 + 6*6 + 6*2 + 2*1 + 2*6 + 2*2).

Crossrefs

Cf. A085444.

Sequence in context: A044763 A165676 A160783 * A048511 A206128 A333101

Adjacent sequences: A085442 A085443 A085444 * A085446 A085447 A085448

Keyword

base,fini,full,nonn

Author

Chuck Seggelin (barkeep(AT)plastereddragon.com), Jun 30 2003

Status

approved