21513

Appears in sequences

• a(n) = (d(n)-r(n))/2, where d = A026037 and r is the periodic sequence with fundamental period (1,0,0,1).at n=48A026038
• Nearest integer to n^5/25.at n=13A061003
• Number of ways to tile an n X 1 strip with 1 X 1 squares and 2 X 1 dominoes with the restriction that no three consecutive tiles are of the same type.at n=31A137200
• Partial sums of A033485.at n=40A178855
• Nonnegative walks of length n on the x-axis starting at the origin using steps {1,-1} and visiting no point more than twice.at n=30A212584