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A049646 a(n) = T(n,n+1), array T given by A049639. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A233514 A096262 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

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Last modified March 25 10:19 EDT 2019. Contains 321470 sequences. (Running on oeis4.)