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A211019
Triangle read by rows: T(n,k) = number of squares and rectangles of area 2^(k-1) after 2^n stages in the toothpick structure of A139250, divided by 4, n>=1, k>=1, assuming the toothpicks have length 2.
5
0, 0, 1, 2, 3, 1, 10, 13, 3, 1, 42, 53, 13, 3, 1, 170, 213, 53, 13, 3, 1, 682, 853, 213, 53, 13, 3, 1, 2730, 3413, 853, 213, 53, 13, 3, 1, 10922, 13653, 3413, 853, 213, 53, 13, 3, 1, 43690, 54613, 13653, 3413, 853, 213, 53, 13, 3, 1, 174762, 218453
OFFSET
1,4
COMMENTS
All internal regions in the toothpick structure are squares and rectangles.
FORMULA
T(n,k) = A211016(n,k)/4.
T(n,1) = A020988(n-2), n>=2.
EXAMPLE
Triangle begins:
0;
0, 1;
2, 3, 1;
10, 13, 3, 1;
42, 53, 13, 3, 1;
170, 213, 53, 13, 3, 1;
682, 853, 213, 53, 13, 3, 1;
2730, 3413, 853, 213, 53, 13, 3, 1;
10922, 13653, 3413, 853, 213, 53, 13, 3, 1;
43690, 54613, 13653, 3413, 853, 213, 53, 13, 3, 1;
CROSSREFS
Row sums give 0 together with A014825.
Sequence in context: A247563 A322702 A107855 * A298401 A009026 A046222
KEYWORD
nonn,tabl
AUTHOR
Omar E. Pol, Sep 24 2012
STATUS
approved