OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
EXAMPLE
The sequence of terms together with their divisors begins:
6: {1,2,3,6}
8: {1,2,4,8}
10: {1,2,5,10}
14: {1,2,7,14}
15: {1,3,5,15}
20: {1,2,4,5,10,20}
21: {1,3,7,21}
22: {1,2,11,22}
26: {1,2,13,26}
27: {1,3,9,27}
28: {1,2,4,7,14,28}
33: {1,3,11,33}
34: {1,2,17,34}
35: {1,5,7,35}
38: {1,2,19,38}
39: {1,3,13,39}
44: {1,2,4,11,22,44}
46: {1,2,23,46}
51: {1,3,17,51}
52: {1,2,4,13,26,52}
MAPLE
q:= n-> (l-> nops(l)>2 and isprime(l[-3]))(
sort([numtheory[divisors](n)[]])):
select(q, [$1..200])[]; # Alois P. Heinz, Oct 19 2019
MATHEMATICA
Select[Range[100], Length[Divisors[#]]>2&&PrimeQ[Divisors[#][[-3]]]&]
PROG
(PARI) isA328338(n) = { my(u=numdiv(n)); ((u>2)&&isprime(divisors(n)[u-2])); }; \\ Antti Karttunen, Oct 17 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 16 2019
STATUS
approved