a(n) = phi(n)*T(n), where phi(n) is Euler's totient function (A000010) and T(n) = n*(n+1)/2 is the n-th triangular number (A000217).

A143268

a(n) = phi(n)*T(n), where phi(n) is Euler's totient function (A000010) and T(n) = n*(n+1)/2 is the n-th triangular number (A000217).

Terms

    a(0) =1a(1) =3a(2) =12a(3) =20a(4) =60a(5) =42a(6) =168a(7) =144a(8) =270a(9) =220a(10) =660a(11) =312a(12) =1092a(13) =630a(14) =960a(15) =1088a(16) =2448a(17) =1026a(18) =3420a(19) =1680a(20) =2772a(21) =2530a(22) =6072a(23) =2400a(24) =6500a(25) =4212a(26) =6804a(27) =4872a(28) =12180a(29) =3720

External references