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A093043 Jacobsthal(n)*Fibonacci(n-1). 1
0, 0, 1, 3, 10, 33, 105, 344, 1105, 3591, 11594, 37565, 121485, 393264, 1272413, 4117971, 13325450, 43123017, 139547457, 451587592, 1461364025, 4729080015, 15303613546, 49523551333, 160261550085, 518617316448, 1678280815525 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Form a graph from a triangle and its midpoint triangle. A093043 counts walks of length n between two vertices of the original triangle.

LINKS

Table of n, a(n) for n=0..26.

Index entries for linear recurrences with constant coefficients, signature (1,7,2,-4).

FORMULA

G.f.: x^2(1+2x)/((1+x-x^2)(1-2x-4x^2));

a(n)=A001045(n)*A000045(n-1);

a(n) := (2^n/3-(-1)^n/3)(((1+sqrt(5))/2)^(n-1)/sqrt(5)-((1-sqrt(5))/2)^(n-1)/sqrt(5)).

CROSSREFS

Sequence in context: A115240 A027989 A096483 * A061566 A082398 A053156

Adjacent sequences:  A093040 A093041 A093042 * A093044 A093045 A093046

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Mar 22 2004

STATUS

approved

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Last modified January 21 16:03 EST 2022. Contains 350479 sequences. (Running on oeis4.)