[seqfan] Sum of a(n) first digits of S is a(n+1)
Eric Angelini
Eric.Angelini at kntv.be
Mon Jan 4 17:52:00 CET 2010
Hello SeqFans,
... I couldn't get to sleep yesterday, 'cause I was
trying to find more terms with my poor new 2010 brain...
a) the sum of the a(n) first digits of S is a(n+1)
b) always use the smallest available integer not leading
to a contradiction
S = 4, 10, 50, 59, 98, 99, ...
Could it be that no such S is infinite?
Explanation:
'4' says: "The first 4 digits of S sum up to 10" (--true)
'10' says: "The first 10 digits of S sum up to 50" (--true)
'50' says: "The first 50 digits of S sum up to 58" (--possible)
'59' says: "The first 59 digits of S sum up to 98" (--possible)
'98' says: "The first 98 digits of S sum up to 99" (--?)
etc. (?)
--> This start doesn't work:
S = 4, 10, 50, 58, 99, 900, ...
--> No S can start with 1, 2 or 3
--> Other 4-starts for S:
S = 4, 11, 50, ...
S = 4, 12, 50, ...
S = 4, 13, 50, ...
...
S = 4, 19, 50, ...
--> More 4-starts for S:
S = 4, 11, 51, ...
S = 4, 11, 52, ...
S = 4, 11, 53, ...
...
Help me finding sleep tonight!
;-)
Best,
É.
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