A097703 Numbers n such that m = 216n + 108 satisfies sigma(m) != 2*usigma(m).

1, 4, 7, 10, 12, 13, 16, 19, 22, 24, 25, 28, 31, 34, 37, 40, 43, 46, 49, 52, 55, 58, 60, 61, 62, 64, 67, 70, 73, 76, 79, 82, 84, 85, 87, 88, 91, 94, 97, 100, 103, 106, 109, 112, 115, 118, 121, 122, 124, 127, 130, 133, 136, 137, 139, 142, 144, 145, 148, 151, 154, 157

Offset

1,2

Comments

Conjecture: all numbers of form 3k + 1 are here. Other terms are listed in A097704.

Links

Table of n, a(n) for n=1..62.

Mathematica

usigma[n_] := Block[{d = Divisors[n]}, Plus @@ Select[d, GCD[ #, n/# ] == 1 &]]; Complement[ Range[157], (Select[ Range[37000], DivisorSigma[1, # ] == 2usigma[ # ] &] - 108)/216] (* Robert G. Wilson v, Aug 28 2004 *)

Crossrefs

Complement of A097702. Cf. A063880.

Sequence in context: A222949 A144020 A047845 * A310674 A104036 A214641

Adjacent sequences: A097700 A097701 A097702 * A097704 A097705 A097706

Keyword

nonn

Author

Ralf Stephan, Aug 26 2004

Status

approved