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 A060980 #4 Sep 12 2017 12:08:43
%S A060980 309,408,419,507,518,529,606,617,628,639,705,716,727,738,749,804,815,
%T A060980 826,837,848,859,903,914,925,936,947,958,969,1409,1508,1519,1607,1618,
%U A060980 1629,1706,1717,1728,1739,1805,1816,1827,1838,1849,1904,1915,1926,1937
%N A060980 |First digit - second digit + third digit - fourth digit ...| = 12.
%H A060980 Harvey P. Dale, <a href="/A060980/b060980.txt">Table of n, a(n) for n = 1..1000</a>
%t A060980 Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[ [ 2k - 1 ] ] ], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[ [ 2k ] ] ], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ] ] == 12, Print[ n ] ], {n, 1, 2000} ]
%t A060980 Select[Range[2000],Abs[Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]]==12&] (* _Harvey P. Dale_, Sep 12 2017 *)
%Y A060980 Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.
%K A060980 base,nonn,easy
%O A060980 1,1
%A A060980 _Robert G. Wilson v_, May 10 2001