A025953 Expansion of g.f. 1/((1-2*x)*(1-3*x)*(1-9*x)*(1-11*x)).

1, 25, 420, 5990, 78431, 976275, 11762890, 138612880, 1607750661, 18432396125, 209480782160, 2364808954170, 26557583235691, 297035583017575, 3311510934334230, 36823696010925860, 408634337848437521, 4527140852274248625, 50088017599651395100, 553573407621363023950

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..900

Index entries for linear recurrences with constant coefficients, signature (25,-205,615,-594).

Formula

G.f.: 1/((1-2*x)*(1-3*x)*(1-9*x)*(1-11*x)).

a(n) = -8*2^n/63+9*3^n/16-243*9^n/28+1331*11^n/144. - R. J. Mathar, Jun 20 2013

a(n) = 3^(n+1)-2^(n+1)+20*a(n-1)-99*a(n-2). - Vincenzo Librandi, May 17 2026

Mathematica

a[0]=1; a[1]=25; a[n_]:=a[n]=3^(n+1)-2^(n+1)+20*a[n-1]-99*a[n-2]; Table[a[n], {n, 0, 25}] (* Vincenzo Librandi, May 17 2026 *)

Prog

(Magma) I:=[1, 25]; [n le 2 select I[n] else 3^n-2^n+20*Self(n-1)-99*Self(n-2): n in [1..22]]; // Vincenzo Librandi, May 17 2026

Crossrefs

Sequence in context: A022628 A020838 A025975 * A020595 A001456 A021964

Adjacent sequences: A025950 A025951 A025952 * A025954 A025955 A025956

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Vincenzo Librandi, May 17 2026

Status

approved