Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".
Table of n, a(n) for n=1..17.
Index entries for linear recurrences with constant coefficients, signature (9,0,1,-9).
G.f.: x*(2+x+2*x^2) / ( (x-1)*(9*x-1)*(1+x+x^2) ). - R. J. Mathar, Apr 26 2015
Sequence in context: A224753 A037558 A037494 * A037742 A037637 A163067
Adjacent sequences: A037571 A037572 A037573 * A037575 A037576 A037577