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 A126030 Riordan array (1/(1+x^3),x/(1+x^3)). 1
 1, 0, 1, 0, 0, 1, -1, 0, 0, 1, 0, -2, 0, 0, 1, 0, 0, -3, 0, 0, 1, 1, 0, 0, -4, 0, 0, 1, 0, 3, 0, 0, -5, 0, 0, 1, 0, 0, 6, 0, 0, -6, 0, 0, 1, -1, 0, 0, 10, 0, 0, -7, 0, 0, 1, 0, -4, 0, 0, 15, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,12 COMMENTS Inverse is A111373. Row sums are A050935(n+2). Diagonal sums are an alternating sign version of A000931(n+3) with g.f. 1/(1-x^2+x^3). LINKS Milan Janjic, Binomial Coefficients and Enumeration of Restricted Words, Journal of Integer Sequences, 2016, Vol 19, #16.7.3 FORMULA Number triangle T(n,k)=C(k+(n-k)/3,(n-k)/3)*(-1)^(n-k)*(2*cos(2*pi*(n-k)/3)+1)/3 EXAMPLE Triangle begins .1, .0, 1, .0, 0, 1, .-1, 0, 0, 1, .0, -2, 0, 0, 1, .0, 0, -3, 0, 0, 1, .1, 0, 0, -4, 0, 0, 1, .0, 3, 0, 0, -5, 0, 0, 1, .0, 0, 6, 0, 0, -6, 0, 0, 1, .-1, 0, 0, 10, 0, 0, -7, 0, 0, 1, .0, -4, 0, 0, 15, 0, 0, -8, 0, 0, 1 CROSSREFS Sequence in context: A188170 A212193 A253189 * A111373 A336757 A116376 Adjacent sequences:  A126027 A126028 A126029 * A126031 A126032 A126033 KEYWORD easy,sign,tabl AUTHOR Paul Barry, Dec 15 2006 STATUS approved

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Last modified July 31 07:24 EDT 2021. Contains 346369 sequences. (Running on oeis4.)