79044domain: NAppears in sequencesa(1)=7; a(n),a(n+1) are smallest > a(n-1) such that a(n-1)^2+a(n)^2=a(n+1)^2.at n=11A077035Riordan array (1/((1-x)(1-3x)),x/((1-x)(1-3x))).at n=49A116414Number of n X 3 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 0 1 0 vertically.at n=11A207769