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 A337947 #15 Oct 05 2020 01:02:16 %S A337947 5,11,16,17,18,20,26,27,28,32,35,38,39,40,41,43,45,46,51,53,55,56,57, %T A337947 58,63,65,67,70,71,72,74,75,76,78,79,80,81,82,87,89,93,95,96,98,99, %U A337947 100,101,102,103,104,105,106,109,110,111,112,117,118,119,121,123 %N A337947 Numbers that do not appear in the addition or multiplication table of A337946. %H A337947 Peter Kagey, <a href="/A337947/b337947.txt">Table of n, a(n) for n = 1..10000</a> %e A337947 The addition table of A337946(k) for k=1..5: %e A337947 + | 1 3 7 12 22 %e A337947 ---+------------- %e A337947 1 | 2 4 8 13 23 %e A337947 3 | 6 10 15 25 %e A337947 7 | 14 19 29 %e A337947 12 | 24 34 %e A337947 22 | 44 %e A337947 The multiplication table of A337946(k) for k=1..5: %e A337947 * | 1 3 7 12 22 %e A337947 ---+--------------- %e A337947 1 | 1 3 7 12 22 %e A337947 3 | 9 21 36 66 %e A337947 7 | 49 84 154 %e A337947 12 | 144 264 %e A337947 22 | 484 %e A337947 Neither of these two tables contain 5, 11, 16, 17, 18, or 20. Since each row is strictly increasing, the rest of the two (infinite) tables do not contain these values either. %Y A337947 Cf. A263995, A337657, A337658, A337946. %K A337947 nonn %O A337947 1,1 %A A337947 _Peter Kagey_, Oct 02 2020