[seqfan] most obscure OEIS code ever?

[Douglas McNeil]

%o A178683 (J programming language, see http://www.jsoftware.com)
%o A178683 . aXXXX =: (5 #. ] {::~ [: (i. >./) */&>)@:part"0
%o A178683 . part =: 3 : 'final (, new)^:y <<i.1 0' NB. Here & below due to Hui
%o A178683 . final=: ; @: (<@-.&0"1&.>) @ > @ {:
%o A178683 . new =: (-i.)@# <@:(cat&.>) ]
%o A178683 . cat =: [ ;@:(,.&.>) -@(<.#) {. ]

There are a handful of other sequences with J codes, but this is
probably the most impressive.  Surprisingly, J appears not to be a
parody esolang, which was my first guess-- or if it is, the authors
have admirably moved all-in on the joke and have kept their tongues in
their cheeks for almost twenty years.  One's tempted to suspect a
drunken bet gone horribly, horribly wrong..


Doug

-- 
Department of Earth Sciences
University of Hong Kong