|
|
A234103
|
|
Products p*q*r of distinct primes for which (p*q*r + 1)/2 is prime.
|
|
6
|
|
|
105, 165, 273, 345, 357, 385, 465, 561, 705, 777, 861, 885, 897, 957, 1005, 1045, 1113, 1173, 1185, 1281, 1353, 1545, 1645, 1653, 1677, 1705, 1905, 1965, 2037, 2065, 2121, 2185, 2193, 2233, 2301, 2373, 2445, 2553, 2613, 2865, 2877, 2905, 2985, 3021, 3157
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
EXAMPLE
|
105 = 3*5*7, and (105 + 1)/2 is prime.
|
|
MATHEMATICA
|
t = Select[Range[1, 10000, 2], Map[Last, FactorInteger[#]] == Table[1, {3}] &]; Take[(t + 1)/2, 120] (* A234102 *)
v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A234103 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|