242820

Appears in sequences

• Where A098018(k)=-n.at n=26A098874
• Numbers n such that sigma(n) = 13*phi(n) (where sigma=A000203, phi=A000010).at n=10A171258
• G.f.: (1+x+x^2+x^3)/(1-3*x-3*x^2-3*x^3).at n=9A188714
• Number of tilings of a 10 X n rectangle using 2n pentominoes of shape Y.at n=20A247118