1970730

Appears in sequences

• a(n)=3*a(n-1)+12*a(n-2) for n>=3, a(0)=1, a(1)=3, a(2)=18 .at n=9A133594
• Expansion of e.g.f. -log(1 - x^2 * (exp(x) - 1)).at n=10A366564