[seqfan] Odd [resp. "even"] number as difference of its neighbours

[Eric Angelini]

Hello SeqFans,

T is the lexico-first permutation of
the integers > 0 such that every odd
term a(n) = a(n+1)-a(n-1)

T = 2,1,3,4,5,9,14,6,7,13,20,8,10,11,21,32,
12,15,27,42,16,17,33,50,18,19,37,56,22,
23,45,68,...

And U is the lexico-first permutation of
the integers > 0 such that every even
term a(n) = a(n+1)-a(n-1)

U = 1,2,3,4,7,5,6,11,8,19,9,10,29,12,41,
13,14,27,15,16,31,17,18,35,20,55,21,22,33,...

Best,
É.