|
|
A136355
|
|
Numbers of the form P = product of the first k odd primes where P+2 is composite.
|
|
4
|
|
|
1155, 255255, 4849845, 111546435, 152125131763605, 6541380665835015, 16294579238595022365, 58644190679703485491635, 3929160775540133527939545, 278970415063349480483707695, 20364840299624512075310661735
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
a(1)=1155 because 1157 is not prime.
|
|
MATHEMATICA
|
v=Select[Range[20], !PrimeQ[Product[Prime[k+1], {k, #}]+2]&]; Table[Product[Prime
[k+1], {k, v[[t]]}], {t, Length[v]}] (End)
Select[FoldList[Times, Prime[Range[2, 21]]], CompositeQ[#+2]&] (* Harvey P. Dale, Jun 08 2022 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|