[seqfan] Re: New seq A284172 from David Sycamore looks interesting

[Benoît Jubin]

If I'm not mistaken, one has for n > 6,
a(2n+1) = 2n+3 if (n+2 is prime or n+1 is a P-prime), and 2 else,
a(2n)   = 3n+2 if n+1 is a P-prime, and n+2 else,
where I defined a P-prime as a prime p such that 2p-1 is prime (there
is probably a standard term for that property).

Benoit

On Tue, Mar 21, 2017 at 9:59 PM, Neil Sloane <njasloane at gmail.com> wrote:
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