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.
a(456) = | 4 - 6 | = 2, a(4567) = | 4 - 7 | + | 5 - 6 | = 4.
a064834 n = sum $ take (length nds `div` 2) $
map abs $ zipWith (-) nds $ reverse nds
where nds = a031298_row n
-- Reinhard Zumkeller, Sep 18 2013
f:=proc(n) local t1,t2,i; t1:=convert(n,base,10); t2:=nops(t1); add( abs(t1[i]-t1[t2+1-i]),i=1..floor(t2/2) ); end; [seq(f(n),n=0..120)]; # N. J. A. Sloane, Mar 24 2013
f[n_] := (k = IntegerDigits[n]; l = Length[k]; Sum[ Abs[ k[[i]] - k[[l - i + 1]]], {i, 1, Floor[l/2] } ] ); Table[ f[n], {n, 0, 100} ]
from sympy import floor, ceiling def A064834(n): x, y = str(n), 0 lx2 = len(x)/2 for a,b in zip(x[:floor(lx2)],x[:ceiling(lx2)-1:-1]): y += abs(int(a)-int(b)) return y # Chai Wah Wu, Aug 09 2014
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