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A356002
A family of triangles T(m), m >= 0, read by triangles and then by rows; triangle T(0) is [1; 1, 1]; for m >= 0, triangle T(m+1) is obtained by replacing each subtriangle [t; u, v] in T(m) by [t; 2*t+u, 2*t+v; t+2*u, t+u+v, t+2*v; u, 2*u+v, u+2*v, v].
5
1, 1, 1, 1, 3, 3, 3, 3, 3, 1, 3, 3, 1, 1, 5, 5, 7, 7, 7, 3, 9, 9, 3, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 3, 9, 9, 3, 9, 9, 3, 7, 9, 9, 9, 9, 9, 9, 7, 5, 7, 9, 9, 9, 9, 9, 7, 5, 1, 5, 7, 3, 9, 9, 3, 7, 5, 1, 1, 7, 7, 11, 11, 11, 5, 15, 15, 5, 17, 17, 17, 17, 17
OFFSET
0,5
COMMENTS
We apply the following substitutions to transform T(m) into T(m+1):
t
/ \
/ \
t 2*t+u 2*t+v
/ \ ___\ / \ / \
/ \ / / \ / \
u-----v t+2*u t+u+v t+2*v
/ \ / \ / \
/ \ / \ / \
u---2*u+v--u+2*v--v
and:
u---2*u+v--u+2*v--v
\ / \ / \ /
\ / \ / \ /
u-----v t+2*u t+u+v t+2*v
\ / ___\ \ / \ /
\ / / \ / \ /
t 2*t+u 2*t+v
\ /
\ /
t
T(m) has 3^m+1 rows, and largest term 3^m.
All terms are odd.
As m gets larger, T(m) exhibits interesting fractal features (see illustrations in Links section).
LINKS
Rémy Sigrist, Colored representation of T(6) (the color is function of T(6)(n,k))
Rémy Sigrist, Colored representation of T(6) (the color is function of the 3-adic valuation of T(6)(n,k))
Rémy Sigrist, PARI program
EXAMPLE
Triangle T(0) is:
1
1 1
Triangle T(1) is:
1
3 3
3 3 3
1 3 3 1
Triangle T(2) is:
1
5 5
7 7 7
3 9 9 3
9 9 9 9 9
9 9 9 9 9 9
3 9 9 3 9 9 3
7 9 9 9 9 9 9 7
5 7 9 9 9 9 9 7 5
1 5 7 3 9 9 3 7 5 1
PROG
(PARI) See Links section.
CROSSREFS
See A355855 for a similar sequence.
Cf. A177407.
Sequence in context: A247655 A097675 A141605 * A251551 A073139 A122845
KEYWORD
nonn,tabf
AUTHOR
Rémy Sigrist, Jul 22 2022
STATUS
approved