271669860

Appears in sequences

• a(n)^2 is a triangular number: a(n) = 6*a(n-1) - a(n-2) with a(0)=0, a(1)=1.at n=12A001109
• Denominators of continued fraction convergents to sqrt(8).at n=23A041011
• a(n) = 34*a(n-1) - a(n-2); a(0)=0, a(1)=6.at n=6A082405
• a(n) = (2*Pell(n+1) - (1+(-1)^n))/4.at n=23A105635
• a(2n) = A011900(n), a(2n+1) = A001109(n+1).at n=23A113225
• Expansion of (1-x)/((1-x)^2 - x^2*(1+x)^2).at n=23A116404
• a(n) = Product_{k=1..floor((n-1)/2)} (4 + 4*cos(k*Pi/n)^2).at n=24A152118
• Square roots of [A055872/8]: Their square written in base 8, with some digit appended, is again a square.at n=25A204512
• Expansion of (1 + 6*x + 17*x^2 - x^3 - 3*x^4)/(1 - 6*x^2 + x^4).at n=21A227792