perplexus.info :: Sequences : Seq.(Seq.(Seq.)) seeking sod

Seq.(Seq.(Seq.)) seeking sod (Posted on 2009-03-01)

A sequence {S(x)}, each of whose terms is a positive integer, is defined as:

S(x) = x/2, if x is even, and:

S(x) = x+3, if x is odd

Given that n is an odd positive integer and, S(S(S(n))) = 27, determine sod(n).

Note: sod(n) denotes the sum of the base-10 digits of n.

Submitted by K Sengupta

Rating: 3.0000 (2 votes)

Solution: (Hide)

The required value of sod(n) is 6.(n =105)
For an explanation, refer to the solution submitted by Steve Herman in this location.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
re: True but unprovable	Daniel	2009-03-02 19:34:39
True but unprovable	Steve Herman	2009-03-02 11:05:47
Working Backwards	Steve Herman	2009-03-01 13:27:28

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