[seqfan] Dual sequences A214094 and A214156

Vladimir Shevelev shevelev at bgu.ac.il
Sat Feb 16 18:39:31 CET 2013


Dear SeqFans,

I submitted two dual analogs of Fibonacci numbers without semiprimes. They are
A214094: a(0)=0, a(1)=1; a(n)=a(n-1)+a(n-2), if a(n-1)+a(n-2) is not semiprime; a(n)is maximal prime divisor of a(n-1)+a(n-2), if a(n-1)+a(n-2) is semiprime;
A214156: a(0)=0, a(1)=1; a(n)=a(n-1)+a(n-2), if a(n-1)+a(n-2) is not semiprime; a(n)is minimal prime divisor of a(n-1)+a(n-2), if a(n-1)+a(n-2) is semiprime. 
In case of A214156 I found that the sequence has period of length 36 and thus is bounded. Can anyone  try to find a period
for A214094 or at least indicate possible large limits where a period not appears.

Regards,
Vladimir

 Shevelev Vladimir‎


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