OFFSET
1,1
COMMENTS
Auxiliary sequence for A128694 which gives the number of groups of order a(n).
a(n) is a subset of the composite numbers m having the property that tau(3*m)=tau(m)+2, where tau(m)=A000005(m) (the number of divisors of m). All primes except 3 satisfy this property. - Gary Detlefs, Jan 25 2019
LINKS
Klaus Brockhaus, Table of n, a(n) for n = 1..10000
EXAMPLE
135 = 3^3*5 is a term.
PROG
(Magma) [ n: n in [1..450] | #t eq 2 and ((t[1, 1] eq 2 and t[1, 2] eq 1 and t[2, 1] eq 3 and t[2, 2] le 6) or (t[1, 1] eq 3 and t[1, 2] le 6 and t[2, 2] eq 1)) where t is Factorization(n) ];
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Mar 26 2007
STATUS
approved