[seqfan] Re: Are these really the same?

[jsk]

Hello Seqfans,

That works modulo 9, but with those fixed number of applications of
"digit sum" here is a counter-example:

Let ds mean "digit sum" and
n = 1643167672515498340370909348402406401858234084993949762680683349197479831368168\
2014025753084837762454116390443428916465355679526070412064665117248437480638969\
6058790415826066773688087737227676518961464118683143681953350708130833140639639\
538740724818732645265724985597900306573113.
We have:
n^2 =
2699999999999999999999999999999999999999999999999999999999999999999999999999999\
9999999999999742494859937523201292271236403801491976275501619779755119745808491\
0527820069158674904054638944486283599826641185169676429691118402190061590427140\
5791306001558712987772232083475971894200678632915982383022575218424954389364866\
1102007087040580794100616626264414273954340234467046137286304555636205977822004\
3778276261438603394989653495920407830541452683134052078806818887220410000745320\
0783900304973580975789241141073811261137712997245971009652648325683251247361451\
0769;
ds(n^2) = 2824;
ds(n^2)^2 = 7974976;
ds( ds(n^2)^2 ) = 49;
ds(ds( ds(n^2)^2) ) =13.


Thanks,
Jason.

On Sun, Jan 8, 2012 at 10:20 AM, Veikko Pohjola <veikko at nordem.fi> wrote:
> I produced a sequence identical to A156638 as follows: Numbers n such that the digit sum of the digit sum of the square of the digit sum of n^2 = 4. Can it be proved or disproved that these are really the same?
>
> Veikko Pohjola
>
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