A309772 Least common multiple of prime(n+1)+1 and prime(n)+1.

12, 12, 24, 24, 84, 126, 180, 120, 120, 480, 608, 798, 924, 528, 432, 540, 1860, 2108, 1224, 2664, 2960, 1680, 1260, 4410, 4998, 5304, 2808, 5940, 6270, 7296, 4224, 3036, 9660, 2100, 11400, 12008, 12956, 6888, 4872, 5220, 16380, 17472, 18624, 19206, 19800, 10600

Offset: 1

Author

Daniel Hoyt, Aug 16 2019

Keywords

• nonn
• look

Comments

a(n) = (prime(n)+1)*(prime(n+1)+1)/2 if n is in A066940. - Robert Israel, Aug 16 2019

Links

• Daniel Hoyt, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A008864, A063086 (gcd), A066940, A180617 (product).

Programs

Magma

[Lcm(1+NthPrime(n),1+NthPrime(n+1)):n in [1..50]]; // Marius A. Burtea, Aug 16 2019

Maple

P:= [seq(ithprime(i),i=1..100)]:
seq(ilcm(P[i]+1,P[i+1]+1),i=1..99); # Robert Israel, Aug 16 2019

Mathematica

Array[LCM[Prime[#] + 1, Prime[# + 1] + 1] &, 50] (* Amiram Eldar, Aug 16 2019 *)

Formula

a(n) = lcm(A008864(n+1), A008864(n)) = lcm(prime(n+1)+1, prime(n)+1).