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A126761 {a(k)} is such that, for every positive integer n, the n-th prime = Sum_{k=1..n, gcd(k,n+1)=1} a(k). 1

%I

%S 2,1,3,1,9,-3,3,3,15,-5,17,-9,-5,21,3,-3,33,-25,-1,19,11,-11,25,11,

%T -23,15,25,-25,35,-29,-25,51,43,-59,79,-51,-93,109,79,-73,205,-197,

%U -189,83,-29,153,139,-223,-95,-193,41,371,125,-223,-177,-151,49,409,101

%N {a(k)} is such that, for every positive integer n, the n-th prime = Sum_{k=1..n, gcd(k,n+1)=1} a(k).

%H Rémy Sigrist, <a href="/A126761/b126761.txt">Table of n, a(n) for n = 1..10000</a>

%H Rémy Sigrist, <a href="/A126761/a126761.gp.txt">PARI program for A126761</a>

%e 31 is the 11th prime. So 31 = Sum_{1<=k<=11, gcd(k,12)=1} a(k) = a(1) + a(5) + a(7) + a(11) = 2 + 9 + 3 + 17.

%o (PARI) See Links section.

%Y Cf. A000040.

%K sign

%O 1,1

%A _Leroy Quet_, Feb 22 2007

%E More terms from _Rémy Sigrist_, Feb 06 2019

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Last modified April 1 10:33 EDT 2020. Contains 333159 sequences. (Running on oeis4.)