The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A072389 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A072389

Numbers of the form x*(x+1) * y*(y+1) ("bipronics") with x and y nonnegative integers.
(history; published version)

#22 by N. J. A. Sloane at Mon Aug 19 11:45:43 EDT 2024

STATUS

proposed

approved

#21 by Michel Marcus at Tue Jul 30 10:04:02 EDT 2024

STATUS

editing

proposed

#20 by Michel Marcus at Tue Jul 30 10:03:59 EDT 2024

PROG

(PARI) A003056(n)=(sqrtint(8*n+1)-1)\2

(PARI) A003056(n)=(sqrtint(8*n+1)-1)\2listlist(lim)=my(v=List([0]), t); for(a=1, A003056(lim\4), t=a*(a+1); for(b=a, A003056(lim\t\2), listput(v, b*(b+1)*t))); Set(v) \\ Charles R Greathouse IV, Jul 11 2024

STATUS

proposed

editing

#19 by Yifan Xie at Fri Jul 19 03:42:41 EDT 2024

STATUS

editing

proposed

#18 by Charles R Greathouse IV at Thu Jul 11 12:45:19 EDT 2024

PROG

(PARI) A003056(n)=(sqrtint(8*n+1)-1)\2list(lim)=my(v=List([0]), t); for(a=1, A003056(lim\4), t=a*(a+1); for(b=a, A003056(lim\t\2), listput(v, b*(b+1)*t))); Set(v) \\ Charles R Greathouse IV, Jul 11 2024

STATUS

proposed

editing

Discussion

Thu Jul 18

13:38

OEIS Server: This sequence has not been edited or commented on for a week
yet is not proposed for review.  If it is ready for review, please
visit https://oeis.org/draft/A072389 and click the button that reads
"These changes are ready for review by an OEIS Editor."

Thanks.
  - The OEIS Server

#17 by Yifan Xie at Fri Jun 28 02:56:34 EDT 2024

STATUS

editing

proposed

#16 by Yifan Xie at Fri Jun 28 02:56:31 EDT 2024

CROSSREFS

Cf. A218391 (sorted by (2*x+1)*(2*y+1)).

STATUS

proposed

editing

#15 by Yifan Xie at Fri Jun 28 02:41:52 EDT 2024

STATUS

editing

proposed

Discussion

Fri Jun 28

02:51

Michel Marcus: I don't understand new xref; this sequence is monotone;  A218391 is not; and in the end, I would move this xref to A218391 (turned upside down)

02:56

Yifan Xie: OK.

#14 by Yifan Xie at Fri Jun 28 02:41:40 EDT 2024

CROSSREFS

Cf. A218391 (sorted by (2*x+1)*(2*y+1)).

#13 by Yifan Xie at Fri Jun 28 02:39:52 EDT 2024

COMMENTS

Nonnegative numbers k = a*b = c*d, where a+b = c+d+1. - Yifan Xie, Jun 28 2024

STATUS

approved

editing