30490

Appears in sequences

• Number of hexagonal polyominoes (or hexagonal polyforms, or planar polyhexes) with n cells.at n=9A000228
• Erroneous version of A000228.at n=9A014558
• Maximal troughs in decimal expansions of Pi: positions of troughs equal to 8.at n=33A105276
• Number of polyominoes consisting of 10 regular unit n-gons.at n=3A120104
• G.f. satisfies: A(x) = A(x^2)^3 + x*A(x^2)^2.at n=35A195200
• a(n) = A273059(4n).at n=31A275916
• Recurrence a(n+2) = Sum_{k=0..n} binomial(n,k)*a(k)*a(n+1-k) with a(0)=1, a(1)=-2.at n=9A289068