The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A333821 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A333821

Numbers k that can be represented in the form k = p^3 - q^3 - r^3, where p, q, r are positive integers satisfying p = q + r.
(history; published version)

#13 by N. J. A. Sloane at Sat May 16 02:25:16 EDT 2020

STATUS

proposed

approved

#12 by Wesley Ivan Hurt at Fri Apr 10 00:41:12 EDT 2020

STATUS

editing

proposed

#11 by Wesley Ivan Hurt at Fri Apr 10 00:40:03 EDT 2020

FORMULA

a(n) = 6 * A121741(n).

STATUS

proposed

editing

#10 by Antonio Roldán at Tue Apr 07 05:08:54 EDT 2020

STATUS

editing

proposed

#9 by Antonio Roldán at Tue Apr 07 05:08:38 EDT 2020

FORMULA

a(n) = 6 * A121741(n)

STATUS

proposed

editing

#8 by Antonio Roldán at Mon Apr 06 13:46:10 EDT 2020

STATUS

editing

proposed

#7 by Antonio Roldán at Mon Apr 06 13:43:16 EDT 2020

COMMENTS

An alternative representation of a(n) k is a(n) k = 3*q*r*(q+r), with q, r positive integers, then a(n) k is a multiple of 6.

STATUS

proposed

editing

Discussion

Mon Apr 06

13:45

Antonio Roldán: I will study if A333821 is 6 * A121741. It is possible, because both sequences have polynomial formulas of three variables. If I can try it, I'll add a comment and a crossref. Thanks.

#6 by Wesley Ivan Hurt at Mon Apr 06 13:06:05 EDT 2020

STATUS

editing

proposed

Discussion

Mon Apr 06

13:10

Andrew Howroyd: So is this 6*A121741?

13:12

Andrew Howroyd: I'm reading your comment that says a(n) is a multiple of 6, so testing if the sequence that is 1/6 of this is in oeis already seems a natural thing to try.

#5 by Wesley Ivan Hurt at Mon Apr 06 13:04:40 EDT 2020

EXAMPLE

60 is in this the sequence because 60 = 5^3 - 4^3 - 1^3, with 5 = 4 + 1.

Discussion

Mon Apr 06

13:06

Wesley Ivan Hurt: I changed n to k.  What is a(n)?

#4 by Wesley Ivan Hurt at Mon Apr 06 13:02:17 EDT 2020

NAME

Numbers n k that can be represented in the form nk = p^3 - q^3 - r^3, where p, q, r are positive integers satisfying p = q + r.

COMMENTS

An alternative representation of a(n) is a(n) = 3qr3*q*r*(q+r), with q, r positive integers, then a(n) is a multiple of 6.

EXAMPLE

60 is in this sequence because 60 = 5^3 - 4^3 - 1^3, with 5 = 4 + 1.

STATUS

proposed

editing