130985

Appears in sequences

• Sequence S with the following properties: (i) a(1)=2; (ii) for n in S, a(n)=a(1)+a(2)+...+a(n-1); (iii) for n not in S, a(n)=the smallest number different from a(1), ..., a(n-1) not breaking property (ii).at n=28A121175
• a(n) = A239793(n)/2^(3*n).at n=33A239795
• a(n) = Sum_{1 <= x_1, x_2, x_3 <= n} ( gcd(x_1, n)/gcd(x_1, x_2, x_3, n) )^2.at n=17A371492