OFFSET
0,2
FORMULA
Superseeker suggested (1-x+ 2 I x^2/Sqrt[ -1+ 4 x])/(1-2 x)^2, first 32 terms agreeing.
MATHEMATICA
Table[Sum[(# Conjugate[ # ]&)@ Sum[Binomial[n, t] I^t, {t, 0, k}], {k, 0, n}], {n, 0, 32}] or also CoefficientList[Series[(1-x+2I x^2/Sqrt[ -1+4x])/(1-2x)^2, {x, 0, 32}], x]
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Wouter Meeussen, Mar 06 2004
STATUS
approved