[seqfan] Re: Question on 2F1 from Karol A. Penson

[Harvey P. Dale]

	I have provided a Mma program for A146556 based on Richard Guy's formula.
	Best,
	Harvey

-----Original Message-----
From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Richard Guy
Sent: Tuesday, July 16, 2013 1:16 PM
To: Sequence Fanatics Discussion list
Subject: [seqfan] Re: Question on 2F1 from Karol A. Penson

Dear OEIS,
           I was about to submit seq A146556 but found that it was already in.
           The formula, and its appearance in the PARI program, is more neatly written  a(n)=2*sigma(a(n-1))-a(n-1).

           The example, 1488, 2480, 3472, 4464, 8432, 9424, continues 10416, 21328, 22320, 55056, ..., seems not to be in OEIS.  Curiously, the first term where it might be in doubt is the 31st.

           It would be good if all aliquot sequences, and also divisibility sequences, were available in factored form, but I can understand why this is not so.  If anyone would like the first few hundred terms of A146556 with their factors, I can send.  My labelling is from zero, so the first term containing a factor 31 is the 30th.  R.



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