A097020 Initial terms of chains consisting of four consecutive integers, for none of which is the value of sigma-function divisible by six.

1, 241, 576, 721, 1249, 2449, 12481, 23761, 40897, 65521, 120049, 126001, 128016, 167041, 186049, 211248, 211249, 344449, 374976, 406801, 417697, 451249, 607201, 647521, 665856, 708049, 746641, 766321, 1039681, 1068721, 1092241, 1146096

Offset: 0

Author

Labos Elemer, Aug 23 2004

Keywords

• nonn

Comments

It is believed that in all of such quadruples remainder 3 always arises.

Examples

			n=241: sigma-s for {241,242,243,244} are {242,399,364,434}
whose remainders modulo 6 are {2,3,4,2}.
		

Crossrefs

Cf. A084301.

Programs

Mathematica

SequencePosition[Table[If[Divisible[DivisorSigma[1,n],6],0,1],{n,12*10^5}],{1,1,1,1}][[All,1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 21 2017 *)

Extensions

Definition rephrased by Harvey P. Dale, Oct 21 2017