A258385 - OEIS

%I #16 Sep 08 2022 08:46:12

%S 0,8,648,82944,16000000,4374000000,1613775332736,773738492592128,

%T 467988280328060928,348678440100000000000,313842837672100000000000,

%U 335790511878017502425382912,421272520289832237611045879808,612530145817540311016457192308736

%N a(n) = n^(n+1) * (n-1)^n.

%H Daniel Suteu, <a href="/A258385/b258385.txt">Table of n, a(n) for n = 1..20</a>

%F a(n) ~ 1/e * n^(2n+1). - _Charles R Greathouse IV_, May 28 2015

%F a(n) = A007778(n)*A007778(n-1). - _Michel Marcus_, Jul 07 2015

%e For n=3, a(3) = 3^(3+1) * (3-1)^3 = 3^4 * 2^3 = 81 * 8 = 648.

%t Array[#^(# + 1) (# - 1)^# &, 20] (* _Vincenzo Librandi_, May 29 2015 *)

%o (Sidef)

%o func a(n) {

%o     (n-1)**n * n**(n+1);

%o };

%o 1.to(Math.inf).each { |n|

%o     say a(n);

%o };

%o (PARI) a(n)=n^(n+1)*(n-1)^n \\ _Charles R Greathouse IV_, May 28 2015

%o (Magma) [n^(n+1) * (n-1)^n: n in [1..20]]; // _Vincenzo Librandi_, May 29 2015

%Y Cf. A007778 (n^(n+1)).

%K nonn,easy

%O 1,2

%A _Daniel Suteu_, May 28 2015

%E More terms from _Vincenzo Librandi_, May 29 2015