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A335074 Triangle read by rows: consider a figure made up of a row of n congruent rectangles and the diagonals of all possible rectangles; T(n,k) (1 <= k <= n-1) is the number of vertices on the edge separating rectangles k and k+1. 3
1, 3, 3, 5, 3, 5, 7, 7, 7, 7, 9, 9, 7, 9, 9, 11, 13, 11, 11, 13, 11, 13, 15, 17, 11, 17, 15, 13, 15, 19, 19, 19, 19, 19, 19, 15, 17, 21, 25, 21, 19, 21, 25, 21, 17, 19, 25, 29, 29, 23, 23, 29, 29, 25, 19, 21, 27, 33, 33, 33, 23, 33, 33, 33, 27, 21, 23, 31, 37, 39, 39, 35, 35, 39, 39, 37, 31, 23 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

The terms are from numeric computation - no formula for a(n) is currently known.

LINKS

Table of n, a(n) for n=2..79.

Scott R. Shannon, Image for n = 3 showing the count of the vertices.

Scott R. Shannon, Image for n = 4 showing the count of the vertices.

Scott R. Shannon, Image for n = 7 showing the count of the vertices.

Scott R. Shannon, Image for n = 10 showing the count of the vertices.

Scott R. Shannon, Image for n = 12 showing the count of the vertices.

FORMULA

Row sum n + Row sum A335056(n) = A159065(n).

EXAMPLE

Triangle begins:

1;

3, 3;

5, 3, 5;

7, 7, 7, 7;

9, 9, 7, 9, 9;

11, 13, 11, 11, 13, 11;

13, 15, 17, 11, 17, 15, 13;

15, 19, 19, 19, 19, 19, 19, 15;

17, 21, 25, 21, 19, 21, 25, 21, 17;

19, 25, 29, 29, 23, 23, 29, 29, 25, 19;

21, 27, 33, 33, 33, 23, 33, 33, 33, 27, 21;

23, 31, 37, 39, 39, 35, 35, 39, 39, 37, 31, 23;

CROSSREFS

Cf. A335056, A159065, A331755, A333288, A306302.

Sequence in context: A131832 A255316 A078587 * A239931 A033558 A046217

Adjacent sequences:  A335071 A335072 A335073 * A335075 A335076 A335077

KEYWORD

nonn,tabl

AUTHOR

Scott R. Shannon and N. J. A. Sloane, May 22 2020

STATUS

approved

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Last modified September 17 03:42 EDT 2021. Contains 347478 sequences. (Running on oeis4.)