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Revision History for A280352 (Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A280352 Expansion of Sum_{k>=1} (x/(1 - x))^(k*(k+1)/2).
(history; published version)
#45 by Vaclav Kotesovec at Mon Mar 13 09:11:48 EDT 2023
STATUS

proposed

approved

#44 by Michel Marcus at Fri Feb 24 01:49:52 EST 2023
STATUS

editing

proposed

Discussion
Fri Feb 24 07:01
Vaclav Kotesovec: You are right that it is more about upper and lower bounds.
Sat Feb 25 16:31
Jerzy R Borysowicz: Thank you. I am looking at zeros of b(n), they are easier to find than maxima. If  zk is zero of b,    b(zk)=0, then I think that zk =~ C*sqrt(k)
#43 by Michel Marcus at Fri Feb 24 01:49:35 EST 2023
LINKS

<a href="/index/Com#comp">Index entries for sequences related to compositions</a>

<a href="/index/Com#comp">Index entries for sequences related to compositions</a>

EXAMPLE

[ [1] [5]

[ [2] [3, 1, 1]

[ [3] [1, 3, 1]

[ [4] [1, 1, 3]

[ [5] [2, 2, 1]

[ [6] [2, 1, 2]

[ [7] [1, 2, 2]

STATUS

proposed

editing

#42 by Jerzy R Borysowicz at Thu Feb 23 22:06:11 EST 2023
STATUS

editing

proposed

#41 by Jerzy R Borysowicz at Thu Feb 23 21:29:18 EST 2023
FORMULA

Conjecture: abs(b(n)-1) < 0.0015015, where b(n) = a(n)*sqrt(n)/2^(n-1), for n > 781; b(n) does not have a limit. - Jerzy R Borysowicz, Feb 17 2023

STATUS

proposed

editing

Discussion
Thu Feb 23 22:05
Jerzy R Borysowicz: b(n) looks a bit as the sin function(but it is not). At n=800000 the "period" (the distance between the local maxima(minima) ) is approximately  1812. The maximum 1.014384...  is at 800126 and the minimum .985616... is at 801022. The "period" is approximately  2.3*sqrt(n), it is 1812
 at n=800 000 and 220 at n=10050. The values  of local maxima(minima) change very slowly at n>=800000 ( maybe they have a limit). Thank you for your comment. I will study "attractors" to see if it is a better description than in terms of maxima and minima. Does the sin function has attractors  +-1 ?
#40 by Vaclav Kotesovec at Wed Feb 22 07:14:10 EST 2023
STATUS

editing

proposed

Discussion
Wed Feb 22 11:03
Vaclav Kotesovec: Numerically (from 100000 terms) are these two attractors 1.01438... and 0.98561...
#39 by Vaclav Kotesovec at Wed Feb 22 07:11:17 EST 2023
LINKS

Vaclav Kotesovec, <a href="/A280352/a280352.jpg">Plot of a(n) / (2^(n-1)/sqrt(n)) for n = 1..10000</a>

STATUS

proposed

editing

Discussion
Wed Feb 22 07:14
Vaclav Kotesovec: Yes, there is no limit, but there are two attractors, see the graph. But I think it should be 0.015 instead of 0.0015.
#38 by Jon E. Schoenfield at Fri Feb 17 18:48:25 EST 2023
STATUS

editing

proposed

#37 by Jon E. Schoenfield at Fri Feb 17 18:48:23 EST 2023
FORMULA

G.f.: Sum_{k>=1} (x/(1 - -x))^(k*(k+1)/2).

a(n) = Sum{_{k=1..floor((sqrt(8*n+1)-1)/2)} binomial(n-1,, k*(k+1)/2-1). - Jerzy R Borysowicz, Dec 26 2022

Conjecture: abs(b(n)-1) < 0.0015, where b(n)=) = a(n)*sqrt(n)/2^(n-1), for n> > 781; b(n) does not have a limit. - Jerzy R Borysowicz, Feb 17 2023

STATUS

proposed

editing

#36 by Jerzy R Borysowicz at Fri Feb 17 15:26:51 EST 2023
STATUS

editing

proposed

Discussion
Fri Feb 17 15:28
Jerzy R Borysowicz: ....... the asymptotic behaviour of a(n)

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Last modified August 30 00:57 EDT 2024. Contains 375520 sequences. (Running on oeis4.)