621946

Appears in sequences

• Indices of 9-gonal numbers which are also triangular.at n=5A048907
• Indices of 9-gonal numbers which are also hexagonal.at n=3A048916
• a(0) = a(1) = a(2) = 1; for n > 2, a(n) = (a(n-1) + 1)*(a(n-2) + 1) / a(n-3).at n=12A276123