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 A181940 a(0)=0, and there are a(n) terms between a(n) and the nearest a(n)+1. 1
 0, 1, 0, 2, 0, 1, 3, 1, 0, 2, 4, 2, 0, 1, 3, 5, 3, 1, 0, 2, 4, 6, 4, 2, 0, 1, 3, 5, 7, 5, 3, 1, 0, 2, 4, 6, 8, 6, 4, 2, 0, 1, 3, 5, 7, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 8, 6, 4, 2, 0, 1, 3, 5, 7, 9, 11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 12, 10, 8, 6, 4, 2, 0, 1, 3, 5, 7, 9, 11, 13, 11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 12 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS FORMULA a(A000217(n))=n. EXAMPLE From Peter Luschny, May 30 2020: (Start) Seen as a triangle: [0] [1, 0] [2, 0, 1] [3, 1, 0, 2] [4, 2, 0, 1, 3] [5, 3, 1, 0, 2, 4] [6, 4, 2, 0, 1, 3, 5] [7, 5, 3, 1, 0, 2, 4, 6] [8, 6, 4, 2, 0, 1, 3, 5, 7] [9, 7, 5, 3, 1, 0, 2, 4, 6, 8] [10, 8, 6, 4, 2, 0, 1, 3, 5, 7, 9] [11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10] (End) PROG (PARI) a_list(N)={my(a=vector(2*N), c=0); for(i=2, N, a[i]=c++; my(j=i); for(k=1, c-1, a[j-=(-1)^k*(c-k+1)]=c-k); i+=c); vecextract(a, 2^N-1)} (Python) def T(num_rows):     L, R = [0], [0]     for n in range(1, num_rows):         R.reverse()         R.insert(0, n)         L.extend(R)     return L print(T(14)) # Peter Luschny, May 30 2020 CROSSREFS Sequence in context: A137712 A194711 A168532 * A261209 A340006 A093555 Adjacent sequences:  A181937 A181938 A181939 * A181941 A181942 A181943 KEYWORD nonn AUTHOR Eric Angelini and M. F. Hasler, Apr 03 2012 STATUS approved

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Last modified May 18 19:58 EDT 2021. Contains 344002 sequences. (Running on oeis4.)