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A169947
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Third entry in row n of triangle in A169945.
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3
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1, 3, 8, 16, 29, 49, 82, 130, 205, 305, 450, 654, 947, 1343, 1902, 2648, 3675, 5015, 6824, 9166, 12343, 16393, 21762, 28682, 37695, 49055, 63892, 82610, 106691, 136643, 174862, 222524, 283073, 357691, 451538, 567498, 712817, 890365, 1112040, 1382374, 1717497
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OFFSET
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1,2
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COMMENTS
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a(n) = A143823(n+1) - n - 2.
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 1..64
Index entries for sequences related to carryless arithmetic
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FORMULA
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Wanted: a recurrence. Are any of A169940-A169954 related to any other entries in the OEIS?
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MATHEMATICA
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b[n_, s_] := Module[{sn, m}, If[n<1, 1, sn = Append[s, n]; m = Length[sn]; If[m*(m - 1)/2 == Length[Table[sn[[i]] - sn[[j]], {i, 1, m - 1}, {j, i+1, m}] // Flatten // Union], b[n - 1, sn], 0] + b[n - 1, s]]];
c[n_] := c[n] = b[n - 1, {n}] + If[n == 0, 0, c[n - 1]];
a[n_] := c[n + 1] - n - 2;
Table[Print[n, " ", a[n]]; a[n], {n, 1, 64}] (* Jean-François Alcover, Sep 02 2019, after Alois P. Heinz in A143823 *)
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CROSSREFS
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Related to thickness: A169940-A169954, A061909.
Sequence in context: A025202 A131941 A009858 * A167616 A009439 A000233
Adjacent sequences: A169944 A169945 A169946 * A169948 A169949 A169950
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Aug 01 2010
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EXTENSIONS
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More terms from R. J. Mathar, Aug 02 2010
a(22)-a(28) and connection to A143823 from Nathaniel Johnston, Nov 12 2010
More terms from Alois P. Heinz, Sep 16 2011
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STATUS
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approved
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