[seqfan] Re: A090566.

[M. F. Hasler]

On Tue, Nov 24, 2015 at 2:46 AM, Robert <israel at math.ubc.ca> wrote:

> Presumably you want a(n) >= 1, even if concatenation of a(n-1) and 0 is a
> square (since we don't want leading zeros in the next one).
>
> 1, 6, 4, 9, 61, 504, 100, 489, ...
>
> I'll contribute it.
>

Thanks !
This is less trivial compared to the other sequence which is a(n+1)
= A243091(a(n)),
b.t.w. it could be extended to a(0)=0.
[A243091 is Robert's "q" corrected in the preceding post of this thread.]
I propose https://oeis.org/draft/A264775 :
Square root of concatenation(A090566(n), A090566(n+1)); a(0) = 1.

I apologize for the additional post to this thread which might not interest
all SeqFans...

-- 
Maximilian


> On Nov 23 2015, Neil Sloane wrote:
>
> David or Bob, What about this version of the sequence?
>> a(1) = 1, a(n) = smallest number NOT YET IN THE SEQUENCE such that the
>> concatenation of a(n-1) and a(n) is a square.
>>
>> It starts rather like A082209, 1, 6, 4, 9, 61, 504, 100, ... but it isn't
>> in the OEIS. Oh, maybe it dies - could you check?
>>
>