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A082793 A tribonacci triangle in which the top two northeast and southeast diagonals consist of tribonacci numbers. 2
1, 1, 1, 2, 1, 2, 4, 2, 2, 4, 7, 4, 4, 4, 7, 13, 7, 8, 8, 7, 13, 24, 13, 14, 16, 14, 13, 24, 44, 24, 26, 28, 28, 26, 24, 44 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Uses a Hosoya-like format except that the latter has the Fibonacci recursion. This triangle uses the tribonacci recursion such that every interior number can be obtained by adding the 3 previous numbers, on its diagonal.

REFERENCES

Thomas Koshy, <"Fibonacci and Lucas Numbers with Applications">John Wiley and Sons, 2001, Chapter 15, pages 187-195, "Hosoya's Triangle".

LINKS

Table of n, a(n) for n=1..36.

FORMULA

T(n, j) = T(n-1, j) + T(n-2, j) + T(n-3, j); (every interior number can be obtained by adding the three previous numbers, on its diagonal.)

EXAMPLE

T(7,3) = 14 = (8 + 4 + 2) = T(6,3) + T(5,3) + T(4,3).

CROSSREFS

Cf. A000073, tribonacci numbers, A058071, Hosoya's triangle.

Sequence in context: A145173 A270594 A270706 * A114929 A247321 A152251

Adjacent sequences:  A082790 A082791 A082792 * A082794 A082795 A082796

KEYWORD

nonn

AUTHOR

Gary W. Adamson, May 24 2003

STATUS

approved

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Last modified August 1 17:43 EDT 2021. Contains 346402 sequences. (Running on oeis4.)