

A084921


a(n) = lcm(p1, p+1) where p is the nth prime.


15



3, 4, 12, 24, 60, 84, 144, 180, 264, 420, 480, 684, 840, 924, 1104, 1404, 1740, 1860, 2244, 2520, 2664, 3120, 3444, 3960, 4704, 5100, 5304, 5724, 5940, 6384, 8064, 8580, 9384, 9660, 11100, 11400, 12324, 13284, 13944, 14964, 16020, 16380
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

This sequence consists of terms of sequences A055523 and A055527 for prime n > 2.  Toni Lassila (tlassila(AT)cc.hut.fi), Feb 02 2004


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Index entries for sequences related to lcm's


FORMULA

a(n) = A084920(n)/2 for n > 1; a(n) = A084922(n)*3 for n > 2.
a(n) = A009286(A000040(n)).  Enrique Pérez Herrero, May 17 2012
a(n) ~ 0.5 n^2 log^2 n.  Charles R Greathouse IV, May 15 2013


MATHEMATICA

LCM[#1, #+1]&/@Prime[Range[50]] (* Harvey P. Dale, Oct 09 2018 *)


PROG

(PARI) a(n)=if(n<2, 3, (prime(n)^21)/2) \\ Charles R Greathouse IV, May 15 2013
(Haskell)
a084921 n = lcm (p  1) (p + 1) where p = a000040 n
 Reinhard Zumkeller, Jun 01 2013


CROSSREFS

Cf. A000040, A006093, A008864, A055523, A055527.
Sequence in context: A081621 A073713 A291023 * A070765 A000577 A111758
Adjacent sequences: A084918 A084919 A084920 * A084922 A084923 A084924


KEYWORD

nonn


AUTHOR

Reinhard Zumkeller, Jun 11 2003


STATUS

approved



