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Revision History for A347608

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

Number of interlacing triangles of size n.
(history; published version)

#37 by Alois P. Heinz at Tue May 02 16:04:42 EDT 2023

FORMULA

a(n) = (n(n+1)/2)! \sum_{k=0}^{n(n+1)/2 - 1} 2^{k+1}/k! (Proof under review)

This is the subsequence of A19525 for which the indices are triangular numbers.

CROSSREFS

Cf. A003121. Cf. A19525

KEYWORD

nonn,more,changed

STATUS

editing

approved

#36 by Alois P. Heinz at Mon Apr 24 18:54:40 EDT 2023

STATUS

proposed

editing

Discussion

Mon Apr 24

18:55

Alois P. Heinz: and please do not use TeX or LaTeX notation for the formulas ...

18:59

Alois P. Heinz: ... and then: there seems to be another problem with the formula ...

Thu Apr 27

04:21

Jon E. Schoenfield: “A19525” (in the Formula and Crossrefs sections) is missing a digit.

Tue May 02

16:03

Alois P. Heinz: I checked your formula and got terms 0, 2, 60, 10464, 53624320, 19324958453760, ... which is different from data ...

16:04

Alois P. Heinz: you did not react to pink box comments ...

16:04

Alois P. Heinz: reverting  now  ...

#35 by Arturo Ortiz San Miguel at Mon Apr 24 17:51:06 EDT 2023

STATUS

editing

proposed

Discussion

Mon Apr 24

18:54

Alois P. Heinz: the comment should be signed:  https://oeis.org/wiki/Style_Sheet#Signing_your_name_when_you_contribute_to_an_existing_sequence

#34 by Arturo Ortiz San Miguel at Mon Apr 24 17:49:54 EDT 2023

FORMULA

a(n) = (n(n+1)/2)! \sum_{k=0}^{n(n+1)/2 - 1} 2^{k+1}/k! (Proof under review)

This is the subsequence of A19525 for which the indices are triangular numbers.

CROSSREFS

Cf. A003121. Cf. A19525

STATUS

approved

editing

Discussion

Mon Apr 24

17:50

Arturo Ortiz San Miguel: I believe this is correct and have a proof. If you would like to take a look at it my email is arturo_ortiz@brown.edu

#33 by Michael De Vlieger at Mon May 09 08:35:39 EDT 2022

STATUS

reviewed

approved

#32 by Michel Marcus at Mon May 09 05:46:18 EDT 2022

STATUS

proposed

reviewed

#31 by Dylan Nelson at Mon May 09 05:38:19 EDT 2022

STATUS

editing

proposed

#30 by Dylan Nelson at Mon May 09 05:35:01 EDT 2022

DATA

1, 2, 20, 1744, 2002568, 42263042752, 21686691099024768, 344069541824691045987328, 226788686879114461294165127878656

EXTENSIONS

a(7)-a(9) from Dylan Nelson, May 09 2022

STATUS

approved

editing

#29 by N. J. A. Sloane at Fri Oct 29 12:24:31 EDT 2021

STATUS

reviewed

approved

#28 by Michel Marcus at Fri Oct 29 09:51:11 EDT 2021

STATUS

proposed

reviewed