format for sending updates by email, was Re A093151
N. J. A. Sloane
njas at research.att.com
Thu May 31 21:50:18 CEST 2007
at first sight it seems to me as if
A038860 = { b(k,j) ; k=1,2,3..., j=1,3,5,7... }
A038853 = { b(k,j) ; k=1,2,3..., j=1,2,3,4... }
with b(k,j)=(k+5j)^3-k^3
(and k=0 might be allowed depending on personal idea of cubes)
but I don't have time to think about "completeness" and since I tend
to make small errors when I don't have time...
M.H.
On 5/31/07, Maximilian Hasler <maximilian.hasler at gmail.com> wrote:
> Definitely, any number of the form 5(3k(k+5)+25) = (k+5)^3-k^3
> should be in that sequence, and 1385 is of that form.
> M.H.
>
> On 5/31/07, Tanya Khovanova <tanyakh at tanyakhovanova.com> wrote:
> > Hello Seqfans,
> >
> > Looking at the definitions, A038860 should be a subsequence of A038853; but 1385 is missing in A038853.
> >
> > A038853 Numbers that are divisible by 5 and are differences between two cubes in at least one way.
> > 215, 335, 485, 665, 875, 1115, 1330, 1685, 2015, 2170, 2375, 2680, 2765, 3150, 3185, 3635, 3880, 4095, 4115, 4570, 4625, 4905, 5165, 5320, 5735, 5805, 6130, 6335, 6795, 6965, 7000, 7625, 7875, 7930, 8315, 8920, 9035, 9045, 9260, 9785, 9970, 10305
> >
> > A038860 Numbers n such that n ends with '5' and is difference between two cubes in at least one way.
> > 215, 335, 485, 665, 875, 1115, 1385, 1685, 2015, 2375, 2765, 3185, 3635, 4095, 4115, 4625, 4905, 5165, 5735, 5805, 6335, 6795, 6965, 7625, 7875, 8315, 9035, 9045, 9785, 10305, 10565, 11375, 11655, 12215, 13085, 13095, 13985, 14625, 14915, 15875
> >
> > Tanya
> >
> >
> > _________________________________________________________________
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> >
>
Yes, I have the book. It is problem 157 in this book.
>>
>> Problem 10. Let S be the set of positive integers that, when written in
>> base 10, does not contain the digit 9. Show that the sum of 1/n over all
>> n â€˜
>> S converges and is less than 80. (Problem 157, USSR Olympiad Problem
>> Book).
>>
>> This could make an interesting comment on A007095 (Numbers in base 9,
>> also
>> numbers without 9 as a digit), but can anyone confirm the reference?
>>
>> My guess from a google search is this may be from "The USSR Olympiad
>> Problem
>> Book : Selected Problems and Theorems of Elementary Mathematics" by D. O.
>> Shklarsky, N. N. Chentzov, and I. M. Yaglom (Paperback - Sep 28 1993),
>> however I do not possess a copy.
>>
>> Jeremy Gardiner
>>
>
>
>
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Hello seqfans,
185 is the smallest positive number that doesn't start any sequence. Do you know anything special about 185 that might start a sequence?
The next one is 214 followed by 230.
Tanya
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