|
%I #15 Dec 06 2016 22:18:15
%S 1,3,7,11,15,23,31,35,39,47,55,59,63,71,79,83,95,107,111,119,127,131,
%T 143,159,167,175,179,191,199,207,215,223,239,251,255,263,279,287,299,
%U 311,319,323,335,351,359,383,391,395,399,407,415,419,431,439,447,455,467,479
%N a(n) = number of legs in each part of the symmetric representation of sigma(A279105(n)).
%F a(n) = 2 * A279105(n) - 1.
%e a(3) = 7 = 2 * A279105(3) - 1;
%e 21 is not in the sequence since 11=(21+1)/2 is not in A174793.
%t a174973Q[n_] := Module[{d=Divisors[n]}, Select[Rest[d] - 2*Most[d], #>0&]=={}]
%t a279106[n_]:=2*Select[Range[n], a174973Q] - 1
%t a279106[250] (* sequence data *)
%Y Cf. A174973, A237270, A237271, A237593, A279105.
%K nonn
%O 1,2
%A _Hartmut F. W. Hoft_, Dec 06 2016
|
