OFFSET
1,1
COMMENTS
The first odd term is a(47) = 1365. - Michel Marcus, Nov 21 2015
LINKS
Michel Lagneau, Table of n, a(n) for n = 1..2000
EXAMPLE
630 is in the sequence because the common prime distinct divisors between a(2)=420 and a(3)=630 are 2, 3, 5 and 7.
MAPLE
with(numtheory):a0:={2, 3, 5, 7}:lst:={}:
for n from 1 to 100 do:
ii:=0:
for k from 210 to 50000 while(ii=0) do:
y:=factorset(k):n0:=nops(y):lst1:={}:
for j from 1 to n0 do:
lst1:=lst1 union {y[j]}:
od:
a1:=a0 intersect lst1:
if {k} intersect lst ={} and a1 <> {} and nops(a1)=4
then
printf(`%d, `, k):lst:=lst union {k}:a0:=lst1:ii:=1:
else
fi:
od:
od:
MATHEMATICA
a = {210}; Do[k = 1; While[Nand[! MemberQ[a, k], Length@ Intersection[First /@ FactorInteger@ a[[n - 1]], First /@ FactorInteger@ k] == 4], k++]; AppendTo[a, k], {n, 2, 45}]; a (* Michael De Vlieger, Nov 21 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Nov 20 2015
STATUS
approved