28677

Appears in sequences

• a(1)=a(2)=1, a(n)=a(n-1)+a(n-2) if n is not congruent to 3, a(n)=a(n-1)+a(n/3) if n is congruent to 3.at n=27A078913
• Numbers k such that phi(phi(k)) = sigma(rad(k)).at n=35A173748
• a(n) = Sum_{i+j+k=n, i,j,k >= 1} tau(i)*tau(j)*tau(k), where tau() = A000005().at n=40A191829
• Number of permutations of [n] avoiding {1324, 2341, 2413}.at n=10A294805
• a(n) = 3*(3*n+1)*(9*n+8)/2.at n=26A304504
• Numbers k such that there are exactly four biquadratefree powerful numbers (A338325) between k^2 and (k+1)^2.at n=25A338391