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a(n)=2n+1 where n is such that A083344(n) is zero.
1

%I #5 Oct 15 2013 22:31:55

%S 3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,47,49,51,

%T 53,55,57,59,61,63,65,67,69,71,73,77,79,81,83,85,87,89,91,93,95,97,99,

%U 101,103,105,107,109,111,113,115,119,121,123,125,127,129,131,133,135,137

%N a(n)=2n+1 where n is such that A083344(n) is zero.

%e First two missing odd numbers are 45 and 75; missing terms are in A082452.

%t di[x_] := Apply[LCM, Divisors[x]+1] (*A066715=*)t1=Table[GCD[2*n+1, DivisorSigma[1, 2*n+1]], {n, 1, 2048}]; (*A082457=*)t2=Table[GCD[2*w+1, di[1+2*w]], {w, 1, 2048}]; (*A083344=*)t3=t2-t1; (*A082453=*)1+2*Flatten[Position[Abs[Sign[t3]], 0]];

%Y Cf. A057643, A066715, A000203, A082457, A083344.

%K nonn

%O 1,1

%A _Labos Elemer_, Apr 25 2003