A049644 - OEIS

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A049644

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

0, 0, 3, 3, 5, 5, 9, 9, 13, 13, 21, 21, 25, 25, 37, 37, 45, 45, 57, 57, 65, 65, 85, 85, 93, 93, 117, 117, 129, 129, 145, 145, 161, 161, 193, 193, 205, 205, 241, 241, 257, 257, 281, 281, 301, 301, 345, 345, 361, 361, 401, 401, 425, 425, 461, 461, 485, 485, 541, 541, 557, 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], {n, 0, 25}] (* G. C. Greubel, Dec 07 2017 *)

CROSSREFS

Cf. A049691, A206297.

Sequence in context: A377984 A062130 A151970 * A147472 A146914 A146253

Adjacent sequences: A049641 A049642 A049643 * A049645 A049646 A049647

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Terms a(42) onward added by G. C. Greubel, Dec 10 2017

STATUS

approved