A124434 LCM (least common multiple) of A001043 (sum of consecutive primes) and A001223 (difference of consecutive primes).

5, 8, 12, 36, 24, 60, 36, 84, 156, 60, 204, 156, 84, 180, 300, 336, 120, 384, 276, 144, 456, 324, 516, 744, 396, 204, 420, 216, 444, 1680, 516, 804, 276, 1440, 300, 924, 960, 660, 1020, 1056, 360, 1860, 384, 780, 396, 2460, 2604, 900, 456, 924, 1416, 480, 2460

Offset: 1

Author

Mitch Cervinka (Mitch.Cervinka(AT)eds.com), Dec 15 2006

Keywords

• nonn
• look

Examples

			a(3)=12 because prime(3)=5, prime(4)=7 and lcm(7+5, 7-5) = lcm(12,2) = 12.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001223, A001043.

Programs

Mathematica

LCM[Total[#],#[[2]]-#[[1]]]&/@Partition[Prime[Range[60]],2,1] (* Harvey P. Dale, Apr 19 2013 *)
Join[{5}, Table[(Prime[n + 1]^2 - Prime[n]^2)/2, {n, 2, 59}]] (* Jon Maiga, Jan 17 2019 *)

PARI

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

Formula

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

a(n) = (prime(n+1)^2 - prime(n)^2)/2 for n > 1. - Jon Maiga, Jan 17 2019