581130734

Appears in sequences

• a(n) = (3^n + 1)/2.at n=19A007051
• Number of periodic palindromic structures of length n using a maximum of three different symbols.at n=39A056504
• Number of set partitions with at most 3 blocks; number of Dyck paths of height at most 4; dimension of space of symmetric polynomials in 3 noncommuting variables.at n=20A124302
• a(n) = 3*a(n-1) - a(n-3) + 3*a(n-4), with initial values 2,5,13,40.at n=18A133448
• a(n) = 3*a(n-1) - a(n-3) + 3*a(n-4), with initial values 2,4,13,40.at n=18A133453
• a(0) = 1 and a(n) = (3^n - (-1)^n)/2 for n >= 1.at n=19A152011
• a(n) = (3*9^n + 1)/2.at n=9A199560
• a(1) = 1, then A007051 ((3^n)+1)/2 interleaved with A057198 (5*3^(n-1)+1)/2.at n=37A246360
• a(n) = (-1)^(n+1) * (3^n+1)/2.at n=19A341463
• Cogrowth sequence of the 18-element group S3 X C3 = <S,T,U | S^3, T^2, U^3, (ST)^2, [S,U], [T,U]>.at n=21A378109