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Revision History for A308217

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Showing entries 1-10 | older changes
a(n) is the multiplicative inverse of A001844(n) modulo A001844(n+1); where A001844 is the sequence of centered square numbers.
(history; published version)
#68 by N. J. A. Sloane at Mon Aug 12 02:24:50 EDT 2019
STATUS

reviewed

approved

#67 by Joerg Arndt at Mon Aug 12 01:21:58 EDT 2019
STATUS

proposed

reviewed

#66 by Robert Israel at Sun Aug 11 13:14:35 EDT 2019
STATUS

editing

proposed

#65 by Robert Israel at Sun Aug 11 13:14:28 EDT 2019
FORMULA

From Robert Israel, Aug 11 2019: (Start)

a(n) = 1 + n/2 if n is even, since 0 < 1+n/2 < A001844(n+1) and (1+n/2)*A001844(n)-1 = (n/2)*A001844(n+1).

a(n) = n^2 + 7/2*(n+1) if n is odd, since 0 < n^2+7/2*(n+1) < A001844(n+1) and (n^2+7/2*(n+1))*A001844(n)-1 = (n^2+3*k/2+1/2)*A001844(n+1).

Colin Barker's conjectures easily follow. (End)

#64 by Robert Israel at Sun Aug 11 12:52:31 EDT 2019
LINKS

Robert Israel, <a href="/A308217/b308217.txt">Table of n, a(n) for n = 0..10000</a>

MAPLE

A001844:= n -> 2*n*(n+1)+1:

seq(1/A001844(n) mod A001844(n+1), n=0..100); # Robert Israel, Aug 11 2019

STATUS

approved

editing

#63 by N. J. A. Sloane at Sat Aug 10 23:55:50 EDT 2019
STATUS

proposed

approved

#62 by Daniel Hoyt at Mon May 20 11:34:30 EDT 2019
STATUS

editing

proposed

Discussion
Thu Aug 08
10:04
Daniel Hoyt: I know Neil stated quadratics were boring in the latest numberphile video just now, but at least the related sequences don't say 'less' :)
#61 by Daniel Hoyt at Mon May 20 11:34:26 EDT 2019
COMMENTS

The sequence explores the relationship between the terms of A001844, the sums of consecutive squares. The sequence is an interleaving of A033951 (a number spiral arm) and the natural numbers. The gap between the lower values of A308215 and the upper values of A308217 increase at by 3n; each successive gap increasing by 6.

STATUS

proposed

editing

#60 by Daniel Hoyt at Mon May 20 11:33:27 EDT 2019
STATUS

editing

proposed

#59 by Daniel Hoyt at Mon May 20 11:33:24 EDT 2019
COMMENTS

The sequence explores the relationship between the terms of A001844, the sums of consecutive squares. The sequence is an interleaving of A033951 (a number spiral arm) and the natural numbers. The gap between the lower values of A308215 and the upper values of A308217 at odd n increases increase at 6n3n; each successive gap increasing by 6.

STATUS

proposed

editing