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 A111707 #10 May 22 2021 03:14:00
%S A111707 0,1,4,9,16,25,36,49,64,81,0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,10,12,14,16,
%T A111707 18,0,3,6,9,12,15,18,21,24,27,0,4,8,12,16,20,24,28,32,36,0,5,10,15,20,
%U A111707 25,30,35,40,45,0,6,12,18,24,30,36,42,48,54,0,7,14,21,28,35,42,49,56,63,0,8
%N A111707 a(n) = Sum_{k = 1..ceiling(w/2)} d(k) * d(w+1-k), where (d(1), ..., d(w)) is the decimal expansion of n.
%H A111707 Rémy Sigrist, <a href="/A111707/b111707.txt">Table of n, a(n) for n = 0..10000</a>
%e A111707 a(12) = 1*2 = 2, a(12345) = 1*5 + 2*4 + 3*3 = 22.
%t A111707 Array[Sum[#1[[k]]*#1[[#2 + 1 - k]], {k, Ceiling[#2/2]}] & @@ {IntegerDigits[#], IntegerLength[#]} &, 82, 0] (* _Michael De Vlieger_, May 21 2021 *)
%o A111707 (PARI) a(n) = { my (d=digits(n)); sum (k=1, ceil(#d/2), d[k]*d[#d+1-k]) } \\ _Rémy Sigrist_, May 21 2021
%Y A111707 Cf. A085942.
%K A111707 base,easy,nonn
%O A111707 0,3
%A A111707 _Amarnath Murthy_, Aug 22 2005
%E A111707 More terms from _Joshua Zucker_, May 08 2006
%E A111707 a(0) = 0 prepended and name clarified by _Rémy Sigrist_, May 21 2021