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%I #8 Jun 16 2019 13:13:42
%S 1,3,7,9,11,13,17,19,21,23,29,31,33,37,39,41,43,47,51,53,57,59,61,67,
%T 69,71,73,79,83,87,89,93,97,101,103,107,109,111,113,123,127,129,131,
%U 137,139,141,149,151,157,159,163,167,173,177,179,181,183,191,193,197,199,201,211
%N 1, p and 3p, where p runs through all primes except 2 and 5.
%H Harvey P. Dale, <a href="/A105585/b105585.txt">Table of n, a(n) for n = 1..1000</a>
%p v1:=[1,3,seq(ithprime(i),i=4..100)]; v2:=3*v1; v3:=[op(v1),op(v2)]; v4:=convert(v3, set); convert(%,list); sort(%);
%t Module[{nn=50},Select[Sort[Flatten[Join[{1,3,9},Table[{n,3n},{n,Prime[ Range[ 4,nn]]}]]]],#<=Prime[nn]&]] (* _Harvey P. Dale_, Jun 16 2019 *)
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Sep 03 2008
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