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A073885 a(1)=1, a(n) = smallest positive integer not included earlier such that the n-th partial sum is a prime iff n is a prime. 2

%I

%S 1,2,4,3,7,5,9,8,6,10,12,11,19,13,14,16,17,15,21,20,18,22,24,23,25,26,

%T 27,28,33,29,31,30,32,34,35,36,43,37,38,40,39,41,49,42,45,44,67,46,47,

%U 48,50,51,54,53,52,56,57,55,63,58,60,59,61,64,62,65,69,68,66,70,72,71

%N a(1)=1, a(n) = smallest positive integer not included earlier such that the n-th partial sum is a prime iff n is a prime.

%t For[n=1; s={}; sum=0, n<=100, n++, For[v=1, MemberQ[s, v]||Xor[PrimeQ[n], PrimeQ[sum+v]], v++, Null]; sum+=v; AppendTo[s, a[n]=v]]; a/@Range[100]

%Y Cf. A073886.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Aug 17 2002

%E Edited by _Dean Hickerson_, Oct 22 2002

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Last modified October 28 09:28 EDT 2021. Contains 348327 sequences. (Running on oeis4.)