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%I
%S 45,75,117,147,189,195,225,231,245,315,325,345,363,385,405,441,483,
%T 495,507,525,561,567,585,595,645,663,675,693,715,735,765,775,777,795,
%U 819,845,847,867,875,891,931,945,957,975,1001,1035,1071,1083,1089,1095,1125
%N a(n)=2n+1 where n is such that A083344(n) is not zero.
%e n=22: 2n+1=45, A057643(45)=5520, a(22)=GCD[45,5520]=15 while A066715[45]=3; a(22)=15-3=12.
%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; (*A082452=*)1+2*Flatten[Position[Abs[Sign[t3]], 1]];
%Y Cf. A057643, A066715, A000203, A082457, A083344.
%K nonn
%O 1,1
%A Labos E. (labos(AT)ana.sote.hu), Apr 25 2003
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