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A178899 Numbers which are both primes and problimes (third definition). 1

%I

%S 2,7,11,19,23,43,53,73,79,97,103,109,127,139,151,157,163,181,193,199,

%T 211,1873,1999,2017,2053,2089,2143,2161,2179,2251,2269,2287,2341,2377,

%U 2467,2503,2521,2539,2557,2593,2647,2683,2719,2791,2917,2953,2971,3061,3079

%N Numbers which are both primes and problimes (third definition).

%H Alois P. Heinz, <a href="/A178899/b178899.txt">Table of n, a(n) for n = 1..1000</a>

%F A000040 INTERSECTION A003068.

%p b:= proc(n) option remember; local k;

%p if n=1 then c(2):= 1; 2

%p else k:= ceil (b(n-1) +1/mul((1-1/b(j)), j=1..n-1));

%p c(k):= n; k

%p fi

%p end:

%p a:= proc(n) option remember; local k;

%p if n=1 then b(1)

%p else for k from c(a(n-1))+1 while not isprime (b(k))

%p do od; b(k)

%p fi

%p end:

%p seq (a(n), n=1..50); # _Alois P. Heinz_, Dec 29 2010

%Y Cf. A000040, A003068, A178532.

%K nonn

%O 1,1

%A _Jonathan Vos Post_, Dec 29 2010

%E More terms from _Alois P. Heinz_, Dec 29 2010

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Last modified October 19 02:41 EDT 2019. Contains 328211 sequences. (Running on oeis4.)