18506

Appears in sequences

• Distinct perimeter lengths of polygons with regularly spaced vertices.at n=13A007874
• Composite numbers k such that (Bell(k+1) - Bell(k)) mod k = 1.at n=5A179279
• Constant term of the reduction by x^2->x+1 of the polynomial p(n,x) defined at Comments.at n=17A193044
• Ordered differences of numbers 3^j-2^j, as in A001047.at n=33A205105
• Number of (7+2) X (n+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=11A252391
• G.f.: Product_{i>=1, j>=1, k>=1, l>=1} (1 + x^(i*j*k*l)).at n=15A280486
• 1 - 1/a(n) is the largest resistance value of this form that can be obtained from a resistor network of not more than n one-ohm resistors.at n=17A339548
• Numbers k such that there exists i >= 1 such that k divides 3^3^i + 1.at n=54A367266
• a(n) = index of 2*prime(n) in A381019.at n=32A379811
• Irregular triangle read by rows: row n consists of the coefficients in the expansion of the polynomial (1/(2*w)) * (x^2 + x) * ((((v + w)/2)^(n - 1)) * (x^2 + 2*x + 4 + w) - (((v - w)/2)^(n - 1)) * (x^2 + 2*x + 4 - w)), where v = x^2 + 4*x + 4 and w = sqrt(x^4 + 4*x^3 + 12*x^2 + 20*x + 12).at n=50A386874