[seqfan] Re: A019513, numbers written in the base of double factorial numbers

[Frank Adams-watters]

Probably the author made a mistake.

Franklin T. Adams-Watters


-----Original Message-----
From: Sean A. Irvine <sairvin at gmail.com>
To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
Sent: Sun, Mar 24, 2019 4:19 pm
Subject: [seqfan] A019513, numbers written in the base of double factorial numbers

I'm having trouble reproducing A019513 (numbers written in the base of
double factorial numbers).

The bases for each position are 1, 2, 3, 8, 15, etc.   The problem occurs
at a(30) for which I get the representation 20000 whereas the sequence
lists a(30)=11201.  Both of these do give 30, as 20000 = 2*15 and 11201 =
15 + 8 + 2*3 + 1.  So there must be some extra condition for which
representation to choose.

My first thought was it must be the "smaller" representation, but the
sequence lists a(6)=200 rather than a(6)=111; and a(8)=1000 rather than
a(8)=210.

Ideas?

Sean.

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