A083554 Least common multiple of prime(n+1)-1 and prime(n)-1.

2, 4, 12, 30, 60, 48, 144, 198, 308, 420, 180, 360, 840, 966, 1196, 1508, 1740, 660, 2310, 2520, 936, 3198, 3608, 1056, 2400, 5100, 5406, 5724, 3024, 1008, 8190, 8840, 9384, 10212, 11100, 3900, 4212, 13446, 14276, 15308, 16020, 3420, 18240, 9408

Offset: 1

Author

Labos Elemer, May 22 2003

Keywords

• nonn

Examples

			n=25: a(25) = lcm(97-1, 101-1) = lcm(96,100) = 2400.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006093, A083538-A083555, A058263.

Programs

Mathematica

f[x_] := Prime[x]-1; Table[LCM[f[w+1], f[w]], {w, 1, 128}]

PARI

a(n) = lcm(prime(n+1)-1, prime(n)-1); \\ Michel Marcus, Mar 15 2018

Formula

a(n) = lcm(A006093(n+1), A006093(n)) = lcm(prime(n+1)-1, prime(n)-1).