[seqfan] Re: Sirag numbers.
Harvey P. Dale
hpd1 at nyu.edu
Sat Oct 1 15:04:49 CEST 2011
I took Jack Brennen's comment, added it to A196224, and
implemented it in a Mathematica program in that sequence.
From: seqfan-bounces at list.seqfan.eu
[mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Jack Brennen
Sent: Thursday, September 29, 2011 12:48 PM
To: seqfan at list.seqfan.eu
Subject: [seqfan] Re: Sirag numbers.
Somebody should let him know that these are really easy
to compute. Express J*(J+1) in base 4. If the last two
non-zero digits are either 13 or 33, J is a Sirag number.
For instance, 12*13 == 156, which in base 4 is written as
2130. Last non-zero digits are '13', so it's a Sirag number.
There are 83334 Sirag numbers <= 10^6, which leads to the
obvious conjecture that the density of Sirag numbers is
On 9/29/2011 9:36 AM, Antti Karttunen wrote:
> Not yet in OEIS:
> Seqfan Mailing list - http://list.seqfan.eu/
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