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A111256 a(n) = If Prime[n+2]+Prime[n]+1 is prime then Prime[n+2]+Prime[n]+1 else Prime[n+1]+Prime[n]+1. 1

%I

%S 6,11,17,19,29,31,41,43,53,67,73,79,89,97,107,113,127,129,139,151,157,

%T 163,181,191,199,205,211,217,223,241,259,271,277,289,307,309,321,337,

%U 347,353,361,373,389,391,409,411,439,451,461,463,473,491,499,509,521

%N a(n) = If Prime[n+2]+Prime[n]+1 is prime then Prime[n+2]+Prime[n]+1 else Prime[n+1]+Prime[n]+1.

%C A switch between two sums of primes when the alternating sum is not prime then a direct sequence prime sum is switched.

%t a=Table[If[PrimeQ[Prime[n + 2] + Prime[n] + 1], Prime[n + 2] + Prime[n] + 1, Prime[n + 1] + Prime[n] + 1], {n, 1, 200}]

%K nonn

%O 1,1

%A _Roger L. Bagula_, Nov 01 2005

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Last modified October 22 01:48 EDT 2021. Contains 348160 sequences. (Running on oeis4.)