A169947 Third entry in row n of triangle in A169945.

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

Offset

1,2

Links

Fausto A. C. Cariboni, Table of n, a(n) for n = 1..99 (terms 1..64 from Alois P. Heinz)

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?

a(n) = A143823(n+1) - n - 2. - Nathaniel Johnston, Nov 12 2010

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-François 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) from Nathaniel Johnston, Nov 12 2010

More terms from Alois P. Heinz, Sep 16 2011

Status

approved