a(n) = Sum_{1 <= x_1, x_2, x_3, x_4, x_5 <= n} n/gcd(x_1, x_2, x_3, x_4, x_5, n).

Terms

a(0) =1a(1) =63a(2) =727a(3) =4031a(4) =15621a(5) =45801a(6) =117643a(7) =257983a(8) =529981a(9) =984123a(10) =1771551a(11) =2930537a(12) =4826797a(13) =7411509a(14) =11356467a(15) =16510911a(16) =24137553a(17) =33388803a(18) =47045863a(19) =62968251a(20) =85526461a(21) =111607713a(22) =148035867a(23) =187553641a(24) =244078121a(25) =304088211a(26) =386356147a(27) =474218933a(28) =594823293a(29) =715457421