OFFSET
0,3
COMMENTS
Corresponding imaginary parts: -i^(n*(n+1))*A052928(n+1).
LINKS
Bruno Berselli, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-4,4,-2,-2,4,-4,3,-1).
FORMULA
EXAMPLE
For n=6, sum_(k=0)^6 (k + i^k)^2 = 84 + 6*i, therefore a(6) = 84.
MATHEMATICA
LinearRecurrence[{3, -4, 4, -2, -2, 4, -4, 3, -1}, {1, 1, 2, 10, 35, 59, 84, 132, 213}, 50]
PROG
(Magma) m:=50; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1-2*x+3*x^2+4*x^3+11*x^4-10*x^5+9*x^6)/((1+x)*(1+x^2)^2*(1-x)^4)));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bruno Berselli, Jan 24 2014
STATUS
approved