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A183894
Imaginary part of a Gaussian integer sequence with a Gaussian integer Somos-4 Hankel transform.
4
0, 1, 1, -3, -3, 25, 25, -223, -223, 2217, 2217, -23427, -23427, 258417, 258417, -2941311, -2941311, 34289041, 34289041, -407344771, -407344771, 4913508489, 4913508489, -60018592735, -60018592735, 740910077497, 740910077497, -9228860168451, -9228860168451, 115849095339489, 115849095339489
OFFSET
0,4
COMMENTS
Hankel transform of A183893(n)+I*A183894(n) is the (-4,-4) Somos-4 Gaussian integer sequence A183895(n)+I*A183896(n).
LINKS
FORMULA
a(n) = Im(Sum{k=0..n, C(floor((n+k)/2),k)*I^k*A000108(k)}), I=sqrt(-1).
MATHEMATICA
Table[Im[Sum[I^k*Binomial[2*k, k]*Binomial[Floor[(n + k)/2], k]/(k + 1), {k, 0, n}]], {n, 0, 50}] (* G. C. Greubel, Feb 21 2018 *)
PROG
(PARI) for(n=0, 50, print1(imag(sum(k=0, n, I^k*binomial(2*k, k)* binomial( floor((n+k)/2), k)/(k+1) )), ", ")) \\ G. C. Greubel, Feb 21 2018
(Magma) [Round(Imaginary((&+[(Sqrt(-1))^k*Binomial(2*k, k)*Binomial( Floor((n+k)/2), k)/(k+1): k in [0..n]]))): n in [0..30]]; // G. C. Greubel, Feb 21 2018
CROSSREFS
Sequence in context: A369230 A219909 A092864 * A151438 A355558 A363471
KEYWORD
sign
AUTHOR
Paul Barry, Jan 07 2011
STATUS
approved