A279106 a(n) = number of legs in each part of the symmetric representation of sigma(A279105(n)).

1, 3, 7, 11, 15, 23, 31, 35, 39, 47, 55, 59, 63, 71, 79, 83, 95, 107, 111, 119, 127, 131, 143, 159, 167, 175, 179, 191, 199, 207, 215, 223, 239, 251, 255, 263, 279, 287, 299, 311, 319, 323, 335, 351, 359, 383, 391, 395, 399, 407, 415, 419, 431, 439, 447, 455, 467, 479

Offset

1,2

Links

Table of n, a(n) for n=1..58.

Formula

a(n) = 2 * A279105(n) - 1.

Example

a(3) = 7 = 2 * A279105(3) - 1;
21 is not in the sequence since 11=(21+1)/2 is not in A174793.

Mathematica

a174973Q[n_] := Module[{d=Divisors[n]}, Select[Rest[d] - 2*Most[d], #>0&]=={}]
a279106[n_]:=2*Select[Range[n], a174973Q] - 1
a279106[250] (* sequence data *)

Crossrefs

Cf. A174973, A237270, A237271, A237593, A279105.

Sequence in context: A095100 A036994 A243115 * A172306 A309274 A112714

Adjacent sequences: A279103 A279104 A279105 * A279107 A279108 A279109

Keyword

nonn

Author

Hartmut F. W. Hoft, Dec 06 2016

Status

approved