login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A009286
a(n) = lcm(sigma(n), phi(n)).
4
1, 3, 4, 14, 12, 12, 24, 60, 78, 36, 60, 28, 84, 24, 24, 248, 144, 78, 180, 168, 96, 180, 264, 120, 620, 84, 360, 168, 420, 72, 480, 1008, 240, 432, 48, 1092, 684, 180, 168, 720, 840, 96, 924, 420, 312, 792, 1104, 496, 798, 1860, 288, 1176, 1404, 360, 360, 120, 720, 1260
OFFSET
1,2
FORMULA
From Antti Karttunen, May 26 2017: (Start)
a(n) = A062354(n) / A009223(n).
a(A000040(n)) = A084921(n). - after Enrique Pérez Herrero's May 17 2012 comment in the latter sequence.
(End)
PROG
(PARI) A009286(n) = lcm(sigma(n), eulerphi(n)); \\ Antti Karttunen, May 26 2017
CROSSREFS
KEYWORD
nonn
STATUS
approved