login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A020343
Expansion of 1/((1-5x)(1-8x)(1-9x)).
1
1, 22, 327, 4100, 46781, 503202, 5201827, 52278640, 514595961, 4986022382, 47721236927, 452316244380, 4253691236341, 39747202125562, 369442770633627, 3418759065309320, 31519177212527921, 289676122850156742
OFFSET
0,2
FORMULA
a(n) = 25*5^n/12 -64*8^n/3 +81*9^n/4. - R. J. Mathar, Jun 29 2013
a(0)=1, a(1)=22, a(3)=327; for n>2, a(n) = 22*a(n-1) -157*a(n-2) +360*a(n-3). - Vincenzo Librandi, Jul 03 2013
a(n) = 17*a(n-1) -72*a(n-2) +5^n. - Vincenzo Librandi, Jul 03 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 5 x) (1 - 8 x) (1 - 9 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 03 2013 *)
PROG
(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-5*x)*(1-8*x)*(1-9*x)))); // Vincenzo Librandi, Jul 03 2013
(Magma) I:=[1, 22, 327]; [n le 3 select I[n] else 22*Self(n-1)-157*Self(n-2)+360*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 03 2013
CROSSREFS
Sequence in context: A020571 A021874 A025963 * A025941 A125479 A047868
KEYWORD
nonn,easy
STATUS
approved