A025937 Expansion of 1/((1-2*x)*(1-3*x)*(1-6*x)*(1-7*x)).

1, 18, 211, 2052, 18025, 148806, 1179487, 9089784, 68647909, 510709914, 3756191803, 27381204396, 198197187553, 1426557620142, 10220981500759, 72957382445088, 519164877763357, 3684933735388290, 26099214855723955, 184522579723839060, 1302626522927757721, 9184196481036475158

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (18,-113,288,-252).

Formula

a(n) = -3*6^(n+1)-2^(n+1)/5+7^(n+3)/20+3^(n+2)/4. - R. J. Mathar, May 22 2013

a(n) = 3^(n+1)-2^(n+1)+13*a(n-1)-42*a(n-2). - Vincenzo Librandi, Apr 24 2026

Mathematica

a[0]=1; a[1]=18; a[n_]:=a[n]=3^(n+1)-2^(n+1)+13a[n-1]-42 a[n-2]; Table[a[n], {n, 0, 20}] (* Vincenzo Librandi, Apr 24 2026 *)

Prog

(Magma) I:=[1, 18]; [n le 2 select I[n] else 3^n-2^n+13*Self(n-1)-42*Self(n-2): n in [1..25]]; // Vincenzo Librandi, Apr 24 2026

Crossrefs

Sequence in context: A229270 A261484 A004323 * A021804 A025932 A260569

Adjacent sequences: A025934 A025935 A025936 * A025938 A025939 A025940

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Vincenzo Librandi, Apr 24 2026

Status

approved