OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).
FORMULA
G.f.: (-3*x^4+2*x^3-2*x^2+4*x)/(x^5-x^4-x+1).
a(n) = 1 + a(n-4) for n>3.
a(n) = 5 + (2*n - 1 - (2 + (-1)^n)*(11 + 2*i^(n*(n+1))))/8, where i=sqrt(-1). [Bruno Berselli, Jun 12 2013]
EXAMPLE
a(11) = 6:
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MAPLE
a:= n-> iquo(n, 4, 'r') +[0, 4, 2, 4][r+1]:
seq(a(n), n=0..80);
MATHEMATICA
RecurrenceTable[{a[0] == 0, a[1] == 4, a[2] == 2, a[3] == 4, a[n] == 1 + a[n - 4]}, a[n], {n, 0, 80}] (* Bruno Berselli, Jun 12 2013 *)
LinearRecurrence[{1, 0, 0, 1, -1}, {0, 4, 2, 4, 1}, 90] (* Harvey P. Dale, Jul 03 2019 *)
PROG
(Maxima) makelist(5+(2*n-1-(2+(-1)^n)*(11+2*%i^(n*(n+1))))/8, n, 0, 80); /* Bruno Berselli, Jun 12 2013 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Jun 12 2013
STATUS
approved