A049649 - OEIS

A049649

T(n,n+3), array T given by A049639.

1, 1, 4, 5, 7, 8, 11, 14, 17, 18, 23, 28, 31, 34, 41, 46, 51, 54, 61, 70, 75, 78, 89, 100, 105, 110, 123, 130, 137, 144, 153, 168, 177, 182, 199, 216, 223, 230, 249, 260, 269, 278, 291, 312, 323, 330, 353, 372, 381, 392, 413, 430, 443, 454, 473, 500, 513, 520, 549, 578, 587, 602

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Sean A. Irvine, Table of n, a(n) for n = 0..500 (terms 1..76 from G. C. Greubel)

MATHEMATICA

T[0 | 1, 0 | 1] = 0; T[0 | 1, _] = T[_, 0 | 1] = 1; T[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[T[n, n + 3], {n, 0, 50}] (* G. C. Greubel, Dec 05 2017 *)

CROSSREFS

Cf. A049639.

Sequence in context: A120753 A188322 A139201 * A050575 A081452 A047492

Adjacent sequences: A049646 A049647 A049648 * A049650 A049651 A049652

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Terms a(37) onward added by G. C. Greubel, Dec 10 2017

Missing a(0)=1 inserted by Sean A. Irvine, Aug 06 2021

STATUS

approved