This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A093906 #8 Apr 03 2024 15:15:55
%S A093906 1,3,6,7,12,13,14,15,24,27,28,29,30,31,48,49,54,57,58,59,60,61,62,63,
%T A093906 97,98,108,109,114,117,118,119,120,123,124,127,194,197,217,218,219,
%U A093906 228,229,237,238,239,240,241,246,247,248,249,389,394,434,439,457,458,479,482,492,493,497,498,499,788,789,878,879,917,959,984,985,986,994,997,998,1579,1757,1758,1759,1968,1971,1988,1994,1997,3514,3517,3518,3989,7028,7034,7037,7978,14074,28148
%N A093906 Start with {2} and close under the operations XY and XY+1; sequence gives complete list of numbers that do not appear.
%C A093906 If we start with {2} and close under the operations XY-1 and XY+1, we get the complement of A014574 (midpoints of twin primes), except for the absence of 1.
%Y A093906 Cf. A009388 and A009293.
%K A093906 nonn,fini,full
%O A093906 1,2
%A A093906 _Franklin T. Adams-Watters_, May 25 2004
%E A093906 Corrected by _Don Reble_, May 25 2004