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 A171913 Van Eck sequence (cf. A181391) starting with a(1) = 3. 1
 3, 0, 0, 1, 0, 2, 0, 2, 2, 1, 6, 0, 5, 0, 2, 6, 5, 4, 0, 5, 3, 20, 0, 4, 6, 9, 0, 4, 4, 1, 20, 9, 6, 8, 0, 8, 2, 22, 0, 4, 11, 0, 3, 22, 6, 12, 0, 5, 28, 0, 3, 8, 16, 0, 4, 15, 0, 3, 7, 0, 3, 3, 1, 33, 0, 5, 18, 0, 3, 7, 11, 30, 0, 5, 8, 23, 0, 4, 23, 3, 11, 10, 0, 6, 39, 0, 3, 7, 18, 22 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A van Eck sequence is defined recursively by a(n+1) = min { k > 0 | a(n-k) = a(n) } or 0 if this set is empty, i.e., a(n) does not appear earlier in the sequence. - M. F. Hasler, Jun 12 2019 LINKS FORMULA a(n+1) = A181391(n) up to the first occurrence of a(1) = 3 in A181391. - M. F. Hasler, Jun 15 2019 MATHEMATICA t = {3}; Do[ d = Quiet[Check[Position[t, Last[t]][[-2]][[1]], 0]]; If[d == 0, x = 0, x = Length[t] - d]; AppendTo[t, x], 100] t  (* Horst H. Manninger, Sep 08 2020 *) PROG (PARI) A171913_vec(N, a=3, i=Map())={vector(N, n, a=if(n>1, iferr(n-mapget(i, a), E, 0)+mapput(i, a, n), a))} \\ M. F. Hasler, Jun 15 2019 CROSSREFS Cf. A181391, A171911, ..., A171918 (same but starting with 0, 1, ..., 8). Sequence in context: A324862 A324864 A331509 * A074936 A035655 A239446 Adjacent sequences:  A171910 A171911 A171912 * A171914 A171915 A171916 KEYWORD nonn AUTHOR N. J. A. Sloane, Oct 22 2010 EXTENSIONS Name edited and cross-references added by M. F. Hasler, Jun 15 2019 STATUS approved

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Last modified October 25 04:05 EDT 2020. Contains 338011 sequences. (Running on oeis4.)