The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #20 Jan 07 2025 19:06:23
%S 0,0,3,20,95,394,1519,5592,19935,69398,237215,799204,2661295,8776962,
%T 28714191,93300656,301392575,968682286,3099626047,9879746748,
%U 31382108175,99375452570,313814790383,988511766280,3106741678495,9743852563014,30502457048799,95320102780052,297398570349935,926510631296818,2882476923066895,8956266393600864,27795307127744895,86165447371545182,266834924374534271
%N a(n) = Sum_{k=1..n-1} binomial(n, k)*2^(n-k-1)*(k-1).
%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (10,-38,68,-57,18).
%F a(n) = (3^(n-1)-1)*(n-3)/2 + 2^(n-1) - 1.
%t LinearRecurrence[{10,-38,68,-57,18},{0,0,3,20,95},35] (* _James C. McMahon_, Jan 07 2025 *)
%K nonn,easy
%O 1,3
%A _Ocean Wong_, Jan 01 2025