A059030 Fourth main diagonal of A059026: a(n) = B(n+3,n) = lcm(n+3,n)/(n+3) + lcm(n+3,n)/n - 1 for all n >= 1.

4, 6, 2, 10, 12, 4, 16, 18, 6, 22, 24, 8, 28, 30, 10, 34, 36, 12, 40, 42, 14, 46, 48, 16, 52, 54, 18, 58, 60, 20, 64, 66, 22, 70, 72, 24, 76, 78, 26, 82, 84, 28, 88, 90, 30, 94, 96, 32, 100, 102, 34, 106, 108, 36, 112, 114, 38, 118, 120, 40, 124, 126, 42, 130

Offset: 1

Author

Asher Auel, Dec 15 2000

Keywords

• nonn
• easy

Crossrefs

Cf. A059026, A059029, A059031.

Programs

Maple

B := (n,m) -> lcm(n,m)/n + lcm(n,m)/m - 1: seq(B(m+3,m),m=1..90);

Formula

G.f.: x(2x^3+2x^2+6x+4)/(1-x^3)^2.