1573204

Appears in sequences

• a(n) = 3*a(n-1) - 4*a(n-2) + 6*a(n-3) - 4*a(n-4), with initial terms 0,1,2,4.at n=21A136427
• The number of 3-permutations that avoid the patterns 132 and 213.at n=19A356728