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Indices of n such that A019565(n)+1 is prime.
3

%I #3 Mar 31 2012 10:23:47

%S 0,1,3,5,7,11,13,15,17,19,23,27,31,35,37,43,45,47,51,57,59,67,73,79,

%T 83,85,97,99,107,111,119,123,133,135,145,151,153,155,159,163,167,173,

%U 175,185,193,201,203,211,213,215,233,245,251,253,257,259,263,267,271,277

%N Indices of n such that A019565(n)+1 is prime.

%e A019565(0)=1, 1+1=2 is prime, so a(1)=0;

%e A019565(1)=2, 2+1=3 is prime, so a(2)=1;

%e A019565(2)=3, 3+1=4 is not prime

%e A019565(3)=6, 6+1=7 is prime, so a(3)=3;

%t A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp = A019565[n] + 1; If[PrimeQ[cp], Print[n]], {n, 0, 1000} ]

%Y Cf. A019565.

%K nonn

%O 0,3

%A _Lei Zhou_, Feb 22 2005