OFFSET
0,3
COMMENTS
Hankel transform of A101499.
Hankel transform of A124431. - Paul Barry, Oct 02 2009
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..114
Paul Barry, Invariant number triangles, eigentriangles and Somos-4 sequences, arXiv preprint arXiv:1107.5490 [math.CO], 2011.
Paul Barry, On the Connection Coefficients of the Chebyshev-Boubaker polynomials, The Scientific World Journal, Volume 2013 (2013), Article ID 657806, 10 pages.
Paul Barry, Riordan arrays, the A-matrix, and Somos 4 sequences, arXiv:1912.01126 [math.CO], 2019.
FORMULA
a(n) = a(-2 - n), a(n) * a(n+5) = 4 * a(n+1) * a(n+4) for all n in Z. - Michael Somos, Jul 20 2014
a(4*n + 1) = 0 for all n in Z. - Michael Somos, Jun 26 2017
MATHEMATICA
a[ n_] := With[{m = n + 1, k = Quotient[n + 2, 4]}, Boole[Mod[m, 4] != 2] (-1)^k 4^(k (m - 2 k))]; (* Michael Somos, Jun 26 2017 *)
PROG
(PARI) {a(n) = my(m=n+1, k=(n+2)\4); (m%4!=2) * (-1)^k * 4^(k*(m - 2*k))}; /* Michael Somos, Jul 20 2014 */
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Jul 05 2009
STATUS
approved