A166010 a(n) = prime(n)^2-4.

0, 5, 21, 45, 117, 165, 285, 357, 525, 837, 957, 1365, 1677, 1845, 2205, 2805, 3477, 3717, 4485, 5037, 5325, 6237, 6885, 7917, 9405, 10197, 10605, 11445, 11877, 12765, 16125, 17157, 18765, 19317, 22197, 22797, 24645, 26565, 27885, 29925, 32037

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Oct 04 2009

Keywords

• nonn
• easy

Comments

Least common multiple of prime(n)-2 and prime(n)+2.

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A066830, A084921, A166011.

Cf. A049001, A084920, A182200; A182174.

Programs

Magma

[NthPrime(n)^2-4: n in [1..41]]; // Bruno Berselli, Apr 17 2012

Mathematica

f[n_]:=LCM[n-2,n+2]; lst={};Do[p=Prime[n];AppendTo[lst,f[p]],{n,5!}]; lst
Prime[Range[5!]]^2 - 4 (* Zak Seidov, Apr 17 2012 *)

PARI

a(n)=prime(n)^2-4 \\ Charles R Greathouse IV, Apr 17 2012

Formula

a(n) = A001248(n)-4 = A040976(n)*A052147(n). [Bruno Berselli, Apr 17 2012]

Extensions

Definition rewritten by Bruno Berselli, Apr 17 2012