Template:Sequence of the Day for September 7

Intended for: September 7, 2013

Timetable

• First draft entered by Alonso del Arte on May 31, 2011 (as a verbatim copy of the write-up from December 7, 2010) ✓
• Draft reviewed by Alonso del Arte on September 3, 2011 ✓
• Draft approved by Daniel Forgues on September 8, 2012 ✓

Yesterday's SOTD * Tomorrow's SOTD

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A051802: Nonzero multiplicative digital root of

n, n   ≥   0

. (Shown below are

a (n), n   ≥   10

.)

{ ..., 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 2, 4, 6, ... }

Here we ignore the zeros in the number when multiplying the digits. (Note that for zero we get the empty product, giving 1.)