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A113772 Determinant of the 2 X 2 matrices where the first column is consecutive triangular numbers and the second column is the corresponding consecutive fibonacci numbers. 0
-2, 0, -2, 5, 15, 49, 120, 279, 605, 1265, 2562, 5070, 9842, 18810 (list; graph; refs; listen; history; internal format)
OFFSET

2,1

FORMULA

a(n) = t(n-1)*f(n)-t(n)*f(n-1) where t(n)=n(n+1)/2 and f(n)=f(n-1)+f(n-2) and f(1)=1 and f(2)=1

EXAMPLE

a(5) = t(4)*f(5)-t(5)*f(4) = 10*5-15*3 = 50-45 = 5

CROSSREFS

Sequence in context: A024308 A059432 A175631 * A033716 A115978 A033751

Adjacent sequences:  A113769 A113770 A113771 * A113773 A113774 A113775

KEYWORD

easy,sign

AUTHOR

Patrick J. Costello (pat.costello(AT)eku.edu), Jan 19 2006

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Last modified February 15 05:45 EST 2012. Contains 205694 sequences.