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 A335886 #8 Jul 25 2020 10:20:23 %S A335886 1,2,22,4,228,44,8,28,3,24,43,288,16,282,433,6,241,64,36,2881,61,222, %T A335886 84,31,86,612,21,66,41,23,6122,166,12,221,68,412,318,863,662,42,1666, %U A335886 244,122,3186,2216,6124,216,683,242,63,864,83,18,62,842,2161,224,4126,361,226,366,48,26,3663,622,126,32,484 %N A335886 The heavy sandwiches sequence (see Comments lines for definition). %C A335886 Imagine we would have a pair of adjacent integers in the sequence like [1951, 2020]. The sandwich would then be made of the rightmost digit of a(n), the leftmost digit of a(n+1) and, in between, the product of those two digits. The pair [1951, 2020] would then produce the sandwich 122. Please note that the pair [2020, 1951] would produce the genuine sandwich 001 (we keep the leading zeros: these are sandwiches after all, not integers). %C A335886 Now we want the sequence to be the lexicographically earliest sequence of distinct positive terms such that the successive sandwiches emerging from the sequence rebuild it, digit after digit. %H A335886 Carole Dubois, <a href="/A335886/b335886.txt">Table of n, a(n) for n = 1..611</a> %e A335886 The first successive sandwiches are: 122, 242, 284, 482, 8324, ... %e A335886 The first one (122) is visible between a(1) = 1 and a(2) = 2; we get the sandwich by inserting the product 2 between 1 and 2. %e A335886 The second sandwich (242) is visible between a(2) = 2 and a(3) = 22; we get this sandwich by inserting the product 4 between 2 and 2. %e A335886 The third sandwich (284) is visible between a(3) = 22 and a(4) = 4; we get this sandwich by inserting the product 8 between 2 and 4. %e A335886 The fourth sandwich (482) is visible between a(4) = 4 and a(5) = 228; we get this sandwich by inserting the product 8 between 4 and 2. %e A335886 The fifth sandwich (8324) is visible between a(5) = 228 and a(6) = 44; we get this sandwich by inserting the product 32 between 8 and 4; etc. %e A335886 The successive sandwiches rebuild, digit by digit, the starting sequence. %Y A335886 Cf. A335600 (the "poor" sandwich sequence). %K A335886 base,nonn %O A335886 1,2 %A A335886 _Eric Angelini_ and _Carole Dubois_, Jun 28 2020