297055

Appears in sequences

• a(1)=a(2)=0; thereafter a(n) = a(n-2)+A238828(n-1)+A238827(n).at n=17A238830
• Number of (n+2)X(2+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00010101 or 01010101.at n=15A261286