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Terms which retain their position in A073885, i.e., terms for which A073885(n) = n.
2

%I #13 Oct 08 2024 07:25:23

%S 1,2,8,10,16,17,20,22,25,26,27,28,31,34,35,36,40,45,56,57,64,68,70,82,

%T 92,93,94,95,96,104,124,137,145,146,147,148,152,165,166,169,170,171,

%U 172,176,177,178,185,188,189,190,197,205,208,214,215,216,217,218,219

%N Terms which retain their position in A073885, i.e., terms for which A073885(n) = n.

%H Robert Israel, <a href="/A073886/b073886.txt">Table of n, a(n) for n = 1..10000</a>

%p S:= [$2..300]:

%p s:= 1: R:= 1:

%p for i from 2 do

%p target:= isprime(i);

%p found:= false;

%p for j from 1 to nops(S) while not found do

%p if isprime(s+S[j]) = target then

%p found:= true;

%p s:= s+S[j];

%p if S[j] = i then R:= R,i fi;

%p S:= subsop(j=NULL,S);

%p fi

%p od;

%p if not found then break fi;

%p od:

%p R; # _Robert Israel_, Oct 07 2024

%t For[n=1; s={}; sum=0, n<=300, n++, For[v=1, MemberQ[s, v]||Xor[PrimeQ[n], PrimeQ[sum+v]], v++, Null]; sum+=v; AppendTo[s, a[n]=v]]; Select[Range[300], a[ # ]==#&]

%Y Cf. A073885.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Aug 17 2002

%E Edited by _Dean Hickerson_, Oct 22 2002