A061650 a(n) = n*20^(n-1).

1, 40, 1200, 32000, 800000, 19200000, 448000000, 10240000000, 230400000000, 5120000000000, 112640000000000, 2457600000000000, 53248000000000000, 1146880000000000000, 24576000000000000000, 524288000000000000000, 11141120000000000000000, 235929600000000000000000

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..100

Index entries for linear recurrences with constant coefficients, signature (40,-400).

Formula

G.f.: x /(1 - 20*x)^2. - Vincenzo Librandi, Jul 02 2018

a(n) = n*20^(n-1).

Mathematica

CoefficientList[Series[(1)/(1 - 20 x)^2, {x, 0, 20}], x] (* Vincenzo Librandi, Jul 02 2018 *)
LinearRecurrence[{40, -400}, {1, 40}, 20] (* Harvey P. Dale, Aug 01 2021 *)

Prog

(PARI) { for (n=1, 100, write("b061650.txt", n, " ", n*20^(n - 1)) ) } \\ Harry J. Smith, Jul 25 2009
(Magma) [n*20^(n-1): n in [1..20]]; // Vincenzo Librandi, Jul 02 2018

Crossrefs

Sequence in context: A152257 A229457 A331350 * A006101 A278381 A251202

Adjacent sequences: A061647 A061648 A061649 * A061651 A061652 A061653

Keyword

easy,nonn

Author

Jason Earls, Jun 14 2001

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 18 2001

Status

approved