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 A215696 a(n)=smallest positive k>n+2 such that k*n+1 is a square. 1

%I #8 Aug 22 2012 10:55:16

%S 8,12,8,12,16,20,24,15,32,36,40,24,48,52,24,33,64,68,72,42,40,84,88,

%T 35,96,100,104,60,112,56,120,69,56,132,48,78,144,148,72,60,160,72,168,

%U 96,91,180,184,63,192,196,88,114,208,212,105,85,104,228,232,84

%N a(n)=smallest positive k>n+2 such that k*n+1 is a square.

%C For any n and k=n+2, 1+k*n=(n+1)^2, so here we consider the case k>n+2. Cases k<n-2 are considered in A076942, A215653.

%H Zak Seidov, <a href="/A215696/b215696.txt">Table of n, a(n) for n = 1..1000</a>

%o (PARI) for(n=1,100,k=n+3;while(!issquare(1+k*n),k++);print1(k","))

%Y Cf. A076942, A215653.

%K nonn

%O 1,1

%A _Zak Seidov_, Aug 21 2012

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