a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A002808 (composite numbers).

A023863

a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A002808 (composite numbers).

Terms

    a(0) =4a(1) =6a(2) =20a(3) =25a(4) =52a(5) =59a(6) =104a(7) =119a(8) =186a(9) =211a(10) =306a(11) =338a(12) =464a(13) =502a(14) =663a(15) =715a(16) =914a(17) =981a(18) =1222a(19) =1297a(20) =1585a(21) =1667a(22) =2004a(23) =2104a(24) =2494a(25) =2615a(26) =3062a(27) =3191a(28) =3700a(29) =3854

External references