%I #8 Nov 15 2019 06:28:38
%S 21,31,43,49,93,99,105,111,141,169,201,211,267,273,303,327,367,391,
%T 399,415,421,427,483,495,517,535,559,651,679,685,699,723,735,787,873,
%U 903,1029,1093,1101,1123,1189,1209,1281,1291,1309,1329,1395
%N Lucky numbers with size of gaps equal to 6 (upper terms).
%H Amiram Eldar, <a href="/A031889/b031889.txt">Table of n, a(n) for n = 1..10000</a>
%Y Cf. A000959.
%K nonn
%O 1,1
%A _Patrick De Geest_