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A330883 A variation of the 'viral sequence' A334355; the same rules for a(n) apply but all numbers must be prime. 1

%I

%S 2,7,3,5,11,13,17,31,29,19,23,41,37,43,53,61,47,67,59,73,83,71,79,89,

%T 101,103,107,97,113,131,109,127,149,137,139,151,179,163,167,157,173,

%U 181,191,193,227,197,199,211,251,223,233,239,263,229,257,269,271,241,281,277,293,311,307

%N A variation of the 'viral sequence' A334355; the same rules for a(n) apply but all numbers must be prime.

%C See A334355 for a description of the rules determining a(n). This sequence follows the same rules except that all terms must be prime.

%C Note that as the sequence starts with 2,7,3,... where 2+7+1=10 is a nonprime and 7+3+1=11 is a prime, like A334355 the terms in this sequence are therefore locked into a pattern of alternating pairs which when 1 is added form a nonprime and then a prime.

%H Scott R. Shannon, <a href="/A330883/b330883.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 2, the smallest prime.

%e a(2) = 7 as a(1)+a(2) = 2+7 = 9 is a composite. Note that a(2) could not be 4 or 6 as only prime numbers are allowed, nor could it be 3 or 5 as 2+3=5 is a prime and 2+5=7 is a prime.

%e a(3) = 3 as a(2)+a(3) = 7+3 = 10 is a composite, and 3 is the smallest prime not yet appearing that sums with 7 to form a composite.

%Y Cf. A334355, A000040, A002808, A001043.

%K nonn

%O 1,1

%A _Scott R. Shannon_ and _Eric Angelini_, Apr 30 2020

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Last modified July 30 19:33 EDT 2021. Contains 346359 sequences. (Running on oeis4.)