[seqfan] Mystery tour with a(n)=sigma(a(n-1))
Eric Angelini
Eric.Angelini at kntv.be
Mon Feb 15 19:38:31 CET 2010
Hello SeqFans,
... might A007497 and A051572 converge in the (far, far)
future at some point?
They have the same definition a(n)=sigma(a(n-1)), but
different starts:
http://www.research.att.com/~njas/sequences/A007497
http://www.research.att.com/~njas/sequences/A051572
If we start with 9,13,14,22,23,... we'll bump into A007497
If we start with 10,11,17,18,39,... we'll join A051572
But what about starting with 16? Where does it go?
16->31->32->63->104->210->576->1651->1792->4088->8880...
More (mysterious so far) starts:
19->20->42->96->252->728->1680->5952->16256->32640...
27->40->90->234->546->1344->4064->8064->26520...
I've used this b-file (from A000005):
http://www.research.att.com/~njas/sequences/b000203.txt
Best,
É.
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