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A169947 Third entry in row n of triangle in A169945. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A143823(n+1) - n - 2.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..64

Index entries for sequences related to carryless arithmetic

FORMULA

Wanted: a recurrence. Are any of A169940-A169954 related to any other entries in the OEIS?

MATHEMATICA

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-Fran├žois Alcover, Sep 02 2019, after Alois P. Heinz in A143823 *)

CROSSREFS

Related to thickness: A169940-A169954, A061909.

Sequence in context: A025202 A131941 A009858 * A167616 A009439 A000233

Adjacent sequences:  A169944 A169945 A169946 * A169948 A169949 A169950

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Aug 01 2010

EXTENSIONS

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

STATUS

approved

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Last modified January 26 14:08 EST 2020. Contains 331280 sequences. (Running on oeis4.)