A014938 a(1)=1, a(n) = n*21^(n-1) + a(n-1).

1, 43, 1366, 38410, 1010815, 25515421, 625878268, 15034586596, 355440320845, 8298240786655, 191776931546866, 4395106938053518, 100020864586079851, 2262634152933752305, 50921433140756382520, 1140878530467983299336

Offset

1,2

Links

Table of n, a(n) for n=1..16.

Index entries for linear recurrences with constant coefficients, signature (29,-224,196).

Formula

G.f.: x/((1 - x)*(1 - 21*x)^2). - Stefano Spezia, Mar 11 2020

Prog

(PARI) a(n) = (1+21^n*(20*n-1))/400; \\ Jinyuan Wang, Mar 11 2020

Crossrefs

Sequence in context: A214100 A229432 A122575 * A235646 A022220 A297028

Adjacent sequences: A014935 A014936 A014937 * A014939 A014940 A014941

Keyword

nonn,easy

Author

Olivier Gérard

Status

approved