A049646 a(n) = T(n,n+1), array T given by A049639.

0, 1, 3, 4, 5, 7, 9, 11, 13, 17, 21, 23, 25, 31, 37, 41, 45, 51, 57, 61, 65, 75, 85, 89, 93, 105, 117, 123, 129, 137, 145, 153, 161, 177, 193, 199, 205, 223, 241, 249, 257, 269, 281, 291, 301, 323, 345, 353, 361, 381, 401, 413, 425, 443, 461, 473, 485, 513, 541, 549, 557

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..75

Mathematica

a[0 | 1, 0 | 1] = 0; a[0 | 1, _] = a[_, 0 | 1] = 1; a[i_, j_] := Module[{slopes, cnt}, slopes = Union@Flatten@Table[(k - j)/(h - i), {h, 0, i - 1}, {k, 0, j - 1}]; cnt[slope_] := Count[Flatten[Table[{h, k}, {h, 0, i - 1}, {k, 0, j - 1}], 1], {h_, k_} /; (k - j)/(h - i) == slope]; Count[cnt /@ slopes, c_ /; c >= 2] + 2]; Table[a[n, n + 1], {n, 0, 25}] (* G. C. Greubel, Dec 07 2017 *)

Crossrefs

Cf. A049639.

Sequence in context: A096262 A308168 A193339 * A033556 A219044 A032507

Adjacent sequences: A049643 A049644 A049645 * A049647 A049648 A049649

Keyword

nonn

Author

Clark Kimberling

Extensions

Terms a(39)-a(60) added by G. C. Greubel, Dec 07 2017

Status

approved