A124434 - OEIS

%I #20 Jan 17 2019 09:20:50

%S 5,8,12,36,24,60,36,84,156,60,204,156,84,180,300,336,120,384,276,144,

%T 456,324,516,744,396,204,420,216,444,1680,516,804,276,1440,300,924,

%U 960,660,1020,1056,360,1860,384,780,396,2460,2604,900,456,924,1416,480,2460

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

%H Vincenzo Librandi, <a href="/A124434/b124434.txt">Table of n, a(n) for n = 1..10000</a>

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

%F a(n) = (prime(n+1)^2 - prime(n)^2)/2 for n > 1. - _Jon Maiga_, Jan 17 2019

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

%t LCM[Total[#],#[[2]]-#[[1]]]&/@Partition[Prime[Range[60]],2,1] (* _Harvey P. Dale_, Apr 19 2013 *)

%t Join[{5}, Table[(Prime[n + 1]^2 - Prime[n]^2)/2, {n, 2, 59}]] (* _Jon Maiga_, Jan 17 2019 *)

%o (PARI) a(n) = my(p = prime(n), q = prime(n+1)); lcm(q+p, q-p); \\ _Michel Marcus_, Mar 15 2018

%Y Cf. A001223, A001043.

%K nonn,look

%O 1,1

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