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User talk:Tilman Piesk/Subgroups of powers of Z2/submission form

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Hi Tilman! Nice sequence. Note that my comments are only my personal view; I am not an editor. You wrote: "I'm not sure, if "tabf" is appropriate here, because the lines in this triangle wouldn't make sense on their own - as e.g. the lines in A022166 do." "tabf" as I understand it indicates just what you expressed by writing the three lines

1, (1 until here for (Z_2)^0)
3, (2 until here for (Z_2)^1)
5, 9, 15, (5 until here for (Z_2)^2)

Here it indicates the concatenation of finite subsequences which arise in a natural manner. The length of these rows is the first difference of the row sums of A022166.

'base': The help file says: Sequence is dependent on base used. Base here means the decimal or binary base of the integers. I do not see why your definition depends on a base. Am I overlooking something? 'new': this will be added automatically when you submit, so you do not have to care. unkn: Again see the help file. I do not think that it is appropriate here. But these are minor details and the editors will take care of it.

What I like much is your example section. Unfortunately many authors do not make good use of it. However note that you should not use non ASCII symbols like ↦ in the submission form. The other part of the OEIS brain has not yet escaped the typewriter age.

But what I am most interested in: is there a way to compute this sequence with a small computer program? Peter Luschny 09:09, 22 May 2011 (UTC)

For sure there are many programs to compute subgroups - and for (Z_2)^n (which is simply nimber addition) that should be very simple. But I don't know anything about that.
'base': You are right, I removed it. I thought this works also for other elementary abelian groups. But for (z_3)^n there is no unique sequence, because the Cayley table can be arranged in different ways - despite the fact, that all elements have the same order.
By the way: What do you think about the line sums of A022166: 1, 2, 5, 16, 67, 374, 2825, ... ? Shouldn't they be here as well? Even the central 2-binomial coefficients are here (A006098).
Tilman Piesk 08:46, 23 May 2011 (UTC)
I think you misunderstand the keyword 'base' as used here. Look at some examples in the database, for instance at A007088. Same with 'unkn'. Your description shows that there is nothing unknown here. And what does 'here' mean? You mention A022166 in your comment and I think this is fine. There is no need to duplicate it in the crosrefs if you mean that. I do not understand your comment about A006098, 1, 3, 35, 1395,.. . Peter Luschny 12:54, 23 May 2011 (UTC)

I just meant to say, that also the row sums 1,2,5,16,67... (number of subgroups of Z2n) could be added to the OEIS. I think they are more important than 1,3,35,1395..., which is already in the OEIS. That's all. It wasn't related to writing this submission form.

'unkn': I thought it's appropriate, because I don't have a formula. The help file reads "anyone who can find a formula or recurrence is urged to send me email", so I added it. Tilman Piesk 10:15, 24 May 2011 (UTC)

Is 1,2,5,16,67... (number of subgroups of Z2n) not A006116? "Because I don't have a formula", I see. Well, so good luck now with your submission! Peter Luschny 11:07, 24 May 2011 (UTC)
Yes it is. Strangely it didn't show up, when I was searching. Thanks.
Here's my submission: A190939 The procedure is extremely cumbersome - hope it was correct, what I made. Tilman Piesk 16:44, 24 May 2011 (UTC)
Congratulation Tilman! Nice sequence. Und aller Anfang ist schwer! Peter Luschny 20:31, 25 May 2011 (UTC)