A176877 - OEIS

A176877

Numbers that are the product of 3 distinct primes a,b and c, such that a+b+c are prime numbers.

165, 273, 345, 385, 399, 435, 561, 595, 651, 665, 715, 759, 777, 795, 885, 903, 957, 1001, 1015, 1065, 1085, 1173, 1209, 1235, 1281, 1335, 1435, 1443, 1463, 1495, 1515, 1533, 1547, 1551, 1615, 1645, 1659, 1677, 1705, 1749, 1767, 1771, 1885, 1947, 1965

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

165=3*5*11; 3+5+11=19,...

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

l[n_]:=Last/@FactorInteger[n]; f[n_]:=First/@FactorInteger[n]; lst={}; Do[If[l[n]=={1, 1, 1}, a=f[n][[1]]; b=f[n][[2]]; c=f[n][[3]]; If[PrimeQ[a+b+c], AppendTo[lst, n]]], {n, 7!}]; lst

With[{upto=2000}, Select[Times@@@Select[Subsets[Prime[Range[ PrimePi[ upto/6]]], {3}], PrimeQ[Total[#]]&]//Union, #<=upto&]] (* Harvey P. Dale, May 15 2017 *)

CROSSREFS

Cf. A006881, A014574, A176875, A176876

Sequence in context: A270175 A319328 A301970 * A356095 A323379 A215967

Adjacent sequences: A176874 A176875 A176876 * A176878 A176879 A176880

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Apr 27 2010

STATUS

approved